diff --git a/.mvn/jvm.config b/.mvn/jvm.config
index 23acc6ad8..52c05b116 100644
--- a/.mvn/jvm.config
+++ b/.mvn/jvm.config
@@ -1 +1,11 @@
 -Xmx1024m -XX:CICompilerCount=1 -XX:TieredStopAtLevel=1 -Djava.security.egd=file:/dev/./urandom
+--add-exports jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.main=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.model=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.processing=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED
+--add-exports jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED
+--add-opens jdk.compiler/com.sun.tools.javac.code=ALL-UNNAMED
+--add-opens jdk.compiler/com.sun.tools.javac.comp=ALL-UNNAMED
diff --git a/.mvn/maven.config b/.mvn/maven.config
index 4b9372844..09af02f19 100644
--- a/.mvn/maven.config
+++ b/.mvn/maven.config
@@ -1,2 +1,3 @@
 -DaltSnapshotDeploymentRepository=repo.spring.io::default::https://repo.spring.io/libs-snapshot-local
+-Djspecify.enabled=true
 -P spring
diff --git a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/RangeConverter.java b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/RangeConverter.java
index 41d90e33b..8c2701f1e 100644
--- a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/RangeConverter.java
+++ b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/RangeConverter.java
@@ -16,6 +16,8 @@
 
 package org.springframework.cloud.task.batch.autoconfigure;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.batch.infrastructure.item.file.transform.Range;
 import org.springframework.core.convert.converter.Converter;
 
@@ -31,7 +33,7 @@
 public class RangeConverter implements Converter<String, Range> {
 
 	@Override
-	public Range convert(String source) {
+	public @Nullable Range convert(String source) {
 		if (source == null) {
 			return null;
 		}
diff --git a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/SingleStepJobAutoConfiguration.java b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/SingleStepJobAutoConfiguration.java
index 5531aa574..04f0dac01 100644
--- a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/SingleStepJobAutoConfiguration.java
+++ b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/SingleStepJobAutoConfiguration.java
@@ -22,8 +22,7 @@
 import org.springframework.batch.core.job.builder.JobBuilder;
 import org.springframework.batch.core.repository.JobRepository;
 import org.springframework.batch.core.step.Step;
-import org.springframework.batch.core.step.builder.SimpleStepBuilder;
-import org.springframework.batch.core.step.builder.StepBuilder;
+import org.springframework.batch.core.step.builder.ChunkOrientedStepBuilder;
 import org.springframework.batch.infrastructure.item.ItemProcessor;
 import org.springframework.batch.infrastructure.item.ItemReader;
 import org.springframework.batch.infrastructure.item.ItemWriter;
@@ -78,16 +77,16 @@ private void validateProperties(SingleStepJobProperties properties) {
 	@ConditionalOnMissingBean
 	@ConditionalOnProperty(prefix = "spring.batch.job", name = "job-name")
 	public Job job(ItemReader<Map<String, Object>> itemReader, ItemWriter<Map<String, Object>> itemWriter) {
-
-		SimpleStepBuilder<Map<String, Object>, Map<String, Object>> stepBuilder = new StepBuilder(
-				this.properties.getStepName(), this.jobRepository)
-			.<Map<String, Object>, Map<String, Object>>chunk(this.properties.getChunkSize(), this.transactionManager)
+		Assert.state(properties.getStepName() != null, "A step name is required");
+		Assert.state(properties.getChunkSize() != null, "A chunkSize is required");
+		var chunkOrientedStepBuilder = new ChunkOrientedStepBuilder(properties.getStepName(), this.jobRepository,
+				this.properties.getChunkSize())
+			.transactionManager(this.transactionManager)
 			.reader(itemReader);
+		chunkOrientedStepBuilder.processor(this.itemProcessor);
+		Step step = chunkOrientedStepBuilder.writer(itemWriter).build();
 
-		stepBuilder.processor(this.itemProcessor);
-
-		Step step = stepBuilder.writer(itemWriter).build();
-
+		Assert.state(this.properties.getJobName() != null, "A job name is required");
 		return new JobBuilder(this.properties.getJobName(), this.jobRepository).start(step).build();
 	}
 
diff --git a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/SingleStepJobProperties.java b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/SingleStepJobProperties.java
index b8be64bde..b0a49cc4e 100644
--- a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/SingleStepJobProperties.java
+++ b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/SingleStepJobProperties.java
@@ -16,6 +16,8 @@
 
 package org.springframework.cloud.task.batch.autoconfigure;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.context.properties.ConfigurationProperties;
 
 /**
@@ -30,23 +32,23 @@ public class SingleStepJobProperties {
 	/**
 	 * Name of the step in the single step job.
 	 */
-	private String stepName;
+	private @Nullable String stepName;
 
 	/**
 	 * The number of items to process per transaction or chunk.
 	 */
-	private Integer chunkSize;
+	private @Nullable Integer chunkSize;
 
 	/**
 	 * The name of the job.
 	 */
-	private String jobName;
+	private @Nullable String jobName;
 
 	/**
 	 * Name of the step in the single step job.
 	 * @return name
 	 */
-	public String getStepName() {
+	public @Nullable String getStepName() {
 		return stepName;
 	}
 
@@ -54,7 +56,7 @@ public String getStepName() {
 	 * Set the name of the step.
 	 * @param stepName name
 	 */
-	public void setStepName(String stepName) {
+	public void setStepName(@Nullable String stepName) {
 		this.stepName = stepName;
 	}
 
@@ -62,7 +64,7 @@ public void setStepName(String stepName) {
 	 * The number of items to process per transaction/chunk.
 	 * @return number of items
 	 */
-	public Integer getChunkSize() {
+	public @Nullable Integer getChunkSize() {
 		return chunkSize;
 	}
 
@@ -70,7 +72,7 @@ public Integer getChunkSize() {
 	 * Set the number of items within a transaction/chunk.
 	 * @param chunkSize number of items
 	 */
-	public void setChunkSize(Integer chunkSize) {
+	public void setChunkSize(@Nullable Integer chunkSize) {
 		this.chunkSize = chunkSize;
 	}
 
@@ -78,7 +80,7 @@ public void setChunkSize(Integer chunkSize) {
 	 * The name of the job.
 	 * @return name
 	 */
-	public String getJobName() {
+	public @Nullable String getJobName() {
 		return jobName;
 	}
 
@@ -86,7 +88,7 @@ public String getJobName() {
 	 * Set the name of the job.
 	 * @param jobName name
 	 */
-	public void setJobName(String jobName) {
+	public void setJobName(@Nullable String jobName) {
 		this.jobName = jobName;
 	}
 
diff --git a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/flatfile/FlatFileItemReaderAutoConfiguration.java b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/flatfile/FlatFileItemReaderAutoConfiguration.java
index 0f2516ef7..7615e0db1 100644
--- a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/flatfile/FlatFileItemReaderAutoConfiguration.java
+++ b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/flatfile/FlatFileItemReaderAutoConfiguration.java
@@ -42,6 +42,7 @@
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.cloud.task.batch.autoconfigure.RangeConverter;
 import org.springframework.context.annotation.Bean;
+import org.springframework.util.Assert;
 
 /**
  * Autconfiguration for a {@code FlatFileItemReader}.
@@ -71,6 +72,8 @@ public FlatFileItemReader<Map<String, Object>> itemReader(@Autowired(required =
 			@Autowired(required = false) LineMapper<Map<String, Object>> lineMapper,
 			@Autowired(required = false) LineCallbackHandler skippedLinesCallback,
 			@Autowired(required = false) RecordSeparatorPolicy recordSeparatorPolicy) {
+		Assert.state(this.properties.getName() != null, "A name is required");
+		Assert.state(this.properties.getResource() != null, "A resource is required");
 		FlatFileItemReaderBuilder<Map<String, Object>> mapFlatFileItemReaderBuilder = new FlatFileItemReaderBuilder<Map<String, Object>>()
 			.name(this.properties.getName())
 			.resource(this.properties.getResource())
@@ -90,6 +93,7 @@ public FlatFileItemReader<Map<String, Object>> itemReader(@Autowired(required =
 		mapFlatFileItemReaderBuilder.skippedLinesCallback(skippedLinesCallback);
 
 		if (this.properties.isDelimited()) {
+			Assert.state(this.properties.getNames() != null, "Names are required");
 			mapFlatFileItemReaderBuilder.delimited()
 				.quoteCharacter(this.properties.getQuoteCharacter())
 				.delimiter(this.properties.getDelimiter())
@@ -99,9 +103,14 @@ public FlatFileItemReader<Map<String, Object>> itemReader(@Autowired(required =
 				.fieldSetMapper(new MapFieldSetMapper());
 		}
 		else if (this.properties.isFixedLength()) {
+			Assert.state(this.properties.getNames() != null, "Names are required");
 			RangeConverter rangeConverter = new RangeConverter();
 			List<Range> ranges = new ArrayList<>();
-			this.properties.getRanges().forEach(range -> ranges.add(rangeConverter.convert(range)));
+			this.properties.getRanges().forEach(range -> {
+				Range result = rangeConverter.convert(range);
+				Assert.state(result != null, "Range String could not converted to non-null range");
+				ranges.add(result);
+			});
 			mapFlatFileItemReaderBuilder.fixedLength()
 				.columns(ranges.toArray(new Range[0]))
 				.names(this.properties.getNames())
diff --git a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/flatfile/FlatFileItemReaderProperties.java b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/flatfile/FlatFileItemReaderProperties.java
index 14d4ab8ea..e72b0f8aa 100644
--- a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/flatfile/FlatFileItemReaderProperties.java
+++ b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/flatfile/FlatFileItemReaderProperties.java
@@ -19,6 +19,8 @@
 import java.util.ArrayList;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.batch.infrastructure.item.file.FlatFileItemReader;
 import org.springframework.batch.infrastructure.item.file.transform.DelimitedLineTokenizer;
 import org.springframework.batch.infrastructure.item.file.transform.Range;
@@ -44,7 +46,7 @@ public class FlatFileItemReaderProperties {
 	 * {@link org.springframework.batch.infrastructure.item.ExecutionContext}. Required if
 	 * {@link #setSaveState} is set to {@code true}.
 	 */
-	private String name;
+	private @Nullable String name;
 
 	/**
 	 * Configure the maximum number of items to be read.
@@ -64,7 +66,7 @@ public class FlatFileItemReaderProperties {
 	/**
 	 * The {@link Resource} to be used as input.
 	 */
-	private Resource resource;
+	private @Nullable Resource resource;
 
 	/**
 	 * Configure whether the reader should be in strict mode (require the input
@@ -118,7 +120,7 @@ public class FlatFileItemReaderProperties {
 	/**
 	 * The names of the fields to be parsed from the file.
 	 */
-	private String[] names;
+	private String @Nullable [] names;
 
 	/**
 	 * Indicates whether the number of tokens must match the number of configured fields.
@@ -150,7 +152,7 @@ public void setSaveState(boolean saveState) {
 	 * keys.
 	 * @return the name
 	 */
-	public String getName() {
+	public @Nullable String getName() {
 		return this.name;
 	}
 
@@ -161,7 +163,7 @@ public String getName() {
 	 * @param name name of the reader instance
 	 * @see org.springframework.batch.infrastructure.item.ItemStreamSupport#setName(String)
 	 */
-	public void setName(String name) {
+	public void setName(@Nullable String name) {
 		this.name = name;
 	}
 
@@ -219,7 +221,7 @@ public void setComments(List<String> comments) {
 	 * The input file for the {@code FlatFileItemReader}.
 	 * @return a Resource
 	 */
-	public Resource getResource() {
+	public @Nullable Resource getResource() {
 		return this.resource;
 	}
 
@@ -228,7 +230,7 @@ public Resource getResource() {
 	 * @param resource the input to the reader.
 	 * @see FlatFileItemReader#setResource(Resource)
 	 */
-	public void setResource(Resource resource) {
+	public void setResource(@Nullable Resource resource) {
 		this.resource = resource;
 	}
 
@@ -391,7 +393,7 @@ public void setRanges(List<String> ranges) {
 	 * Names of each column.
 	 * @return names
 	 */
-	public String[] getNames() {
+	public String @Nullable [] getNames() {
 		return this.names;
 	}
 
@@ -399,7 +401,7 @@ public String[] getNames() {
 	 * The names of the fields to be parsed from the file.
 	 * @param names names of fields
 	 */
-	public void setNames(String[] names) {
+	public void setNames(String @Nullable [] names) {
 		this.names = names;
 	}
 
diff --git a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/flatfile/FlatFileItemWriterAutoConfiguration.java b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/flatfile/FlatFileItemWriterAutoConfiguration.java
index 3ffb705da..2d85b1f20 100644
--- a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/flatfile/FlatFileItemWriterAutoConfiguration.java
+++ b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/flatfile/FlatFileItemWriterAutoConfiguration.java
@@ -35,6 +35,7 @@
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.core.io.WritableResource;
+import org.springframework.util.Assert;
 
 /**
  * Autoconfiguration for a {@code FlatFileItemWriter}.
@@ -47,7 +48,7 @@
 @AutoConfigureAfter(BatchAutoConfiguration.class)
 public class FlatFileItemWriterAutoConfiguration {
 
-	private FlatFileItemWriterProperties properties;
+	private final FlatFileItemWriterProperties properties;
 
 	@Autowired(required = false)
 	private LineAggregator<Map<String, Object>> lineAggregator;
@@ -78,7 +79,8 @@ else if ((this.properties.isFormatted() || this.properties.isDelimited()) && thi
 			throw new IllegalStateException(
 					"A LineAggregator must be configured if the " + "output is not formatted or delimited");
 		}
-
+		Assert.state(this.properties.getName() != null, "name must not be null");
+		Assert.state(this.properties.getResource() != null, "resource must not be null");
 		FlatFileItemWriterBuilder<Map<String, Object>> builder = new FlatFileItemWriterBuilder<Map<String, Object>>()
 			.name(this.properties.getName())
 			.resource((WritableResource) this.properties.getResource())
@@ -101,10 +103,13 @@ else if ((this.properties.isFormatted() || this.properties.isDelimited()) && thi
 				delimitedBuilder.fieldExtractor(this.fieldExtractor);
 			}
 			else {
+				Assert.state(this.properties.getNames() != null, "names must not be null");
 				delimitedBuilder.fieldExtractor(new MapFieldExtractor(this.properties.getNames()));
 			}
 		}
 		else if (this.properties.isFormatted()) {
+			Assert.state(this.properties.getFormat() != null, "format must not be null");
+
 			FlatFileItemWriterBuilder.FormattedBuilder<Map<String, Object>> formattedBuilder = builder.formatted()
 				.format(this.properties.getFormat())
 				.locale(this.properties.getLocale())
@@ -115,6 +120,7 @@ else if (this.properties.isFormatted()) {
 				formattedBuilder.fieldExtractor(this.fieldExtractor);
 			}
 			else {
+				Assert.state(this.properties.getNames() != null, "names must not be null");
 				formattedBuilder.fieldExtractor(new MapFieldExtractor(this.properties.getNames()));
 			}
 		}
@@ -131,7 +137,7 @@ else if (this.lineAggregator != null) {
 	 */
 	public static class MapFieldExtractor implements FieldExtractor<Map<String, Object>> {
 
-		private String[] names;
+		private final String[] names;
 
 		public MapFieldExtractor(String[] names) {
 			this.names = names;
diff --git a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/flatfile/FlatFileItemWriterProperties.java b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/flatfile/FlatFileItemWriterProperties.java
index 0f7c4f9ef..e1ce95a92 100644
--- a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/flatfile/FlatFileItemWriterProperties.java
+++ b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/flatfile/FlatFileItemWriterProperties.java
@@ -18,6 +18,8 @@
 
 import java.util.Locale;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.batch.infrastructure.item.file.FlatFileItemWriter;
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.core.io.Resource;
@@ -34,7 +36,7 @@ public class FlatFileItemWriterProperties {
 	/**
 	 * The {@link Resource} to be used as output.
 	 */
-	private Resource resource;
+	private @Nullable Resource resource;
 
 	/**
 	 * Configure the use of the {@code DelimitedLineAggregator} to generate the output per
@@ -51,7 +53,7 @@ public class FlatFileItemWriterProperties {
 	/**
 	 * Configure the format the {@code FormatterLineAggregator} uses for each item.
 	 */
-	private String format;
+	private @Nullable String format;
 
 	/**
 	 * Configure the {@code Locale} to use when generating the output.
@@ -88,7 +90,7 @@ public class FlatFileItemWriterProperties {
 	/**
 	 * Names of the fields to be extracted into the output.
 	 */
-	private String[] names;
+	private String @Nullable [] names;
 
 	/**
 	 * Configure if the output file is found if it should be appended to. Defaults to
@@ -107,7 +109,7 @@ public class FlatFileItemWriterProperties {
 	 * {@link org.springframework.batch.infrastructure.item.ExecutionContext}. Required if
 	 * {@link #setSaveState} is set to {@code true}.
 	 */
-	private String name;
+	private @Nullable String name;
 
 	/**
 	 * Returns the configured value of whether the state of the reader is persisted.
@@ -157,7 +159,7 @@ public void setSaveState(boolean saveState) {
 	 * keys.
 	 * @return the name
 	 */
-	public String getName() {
+	public @Nullable String getName() {
 		return this.name;
 	}
 
@@ -168,7 +170,7 @@ public String getName() {
 	 * @param name name of the reader instance
 	 * @see org.springframework.batch.infrastructure.item.ItemStreamSupport#setName(String)
 	 */
-	public void setName(String name) {
+	public void setName(@Nullable String name) {
 		this.name = name;
 	}
 
@@ -176,7 +178,7 @@ public void setName(String name) {
 	 * The output file for the {@code FlatFileItemWriter}.
 	 * @return a {@code Resource}
 	 */
-	public Resource getResource() {
+	public @Nullable Resource getResource() {
 		return this.resource;
 	}
 
@@ -185,7 +187,7 @@ public Resource getResource() {
 	 * @param resource the input to the reader.
 	 * @see FlatFileItemWriter#setResource
 	 */
-	public void setResource(Resource resource) {
+	public void setResource(@Nullable Resource resource) {
 		this.resource = resource;
 	}
 
@@ -227,7 +229,7 @@ public void setDelimiter(String delimiter) {
 	 * Names of the fields to be extracted into the output.
 	 * @return An array of field names
 	 */
-	public String[] getNames() {
+	public String @Nullable [] getNames() {
 		return names;
 	}
 
@@ -235,7 +237,7 @@ public String[] getNames() {
 	 * Provide an ordered array of field names used to generate the output of a file.
 	 * @param names An array of field names
 	 */
-	public void setNames(String[] names) {
+	public void setNames(String @Nullable [] names) {
 		this.names = names;
 	}
 
@@ -385,7 +387,7 @@ public void setTransactional(boolean transactional) {
 	 * Format used with the {@code FormatterLineAggregator}.
 	 * @return the format for each item's output.
 	 */
-	public String getFormat() {
+	public @Nullable String getFormat() {
 		return format;
 	}
 
@@ -393,7 +395,7 @@ public String getFormat() {
 	 * Configure the format the {@code FormatterLineAggregator} will use for each item.
 	 * @param format the format for each item's output.
 	 */
-	public void setFormat(String format) {
+	public void setFormat(@Nullable String format) {
 		this.format = format;
 	}
 
diff --git a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/flatfile/package-info.java b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/flatfile/package-info.java
index acab384f1..c0b81c971 100644
--- a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/flatfile/package-info.java
+++ b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/flatfile/package-info.java
@@ -18,4 +18,7 @@
  * Auto-configuration classes for flat file item readers and writers in single-step batch
  * jobs.
  */
+@NullMarked
 package org.springframework.cloud.task.batch.autoconfigure.flatfile;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/jdbc/JdbcBatchItemWriterAutoConfiguration.java b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/jdbc/JdbcBatchItemWriterAutoConfiguration.java
index 02a2ae59e..9eb8d5c87 100644
--- a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/jdbc/JdbcBatchItemWriterAutoConfiguration.java
+++ b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/jdbc/JdbcBatchItemWriterAutoConfiguration.java
@@ -40,6 +40,7 @@
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Import;
+import org.springframework.util.Assert;
 
 /**
  * Autconfiguration for a {@code JdbcBatchItemWriter}.
@@ -85,7 +86,7 @@ public JdbcBatchItemWriter<Map<String, Object>> itemWriter() {
 		catch (Exception ex) {
 			logger.info("Using Default Data Source for the JdbcBatchItemWriter");
 		}
-
+		Assert.state(this.properties.getSql() != null, "sql must not be null");
 		JdbcBatchItemWriterBuilder<Map<String, Object>> jdbcBatchItemWriterBuilder = new JdbcBatchItemWriterBuilder<Map<String, Object>>()
 			.dataSource(writerDataSource)
 			.sql(this.properties.getSql());
diff --git a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/jdbc/JdbcBatchItemWriterProperties.java b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/jdbc/JdbcBatchItemWriterProperties.java
index b9ffdf774..86b0b7bda 100644
--- a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/jdbc/JdbcBatchItemWriterProperties.java
+++ b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/jdbc/JdbcBatchItemWriterProperties.java
@@ -16,6 +16,8 @@
 
 package org.springframework.cloud.task.batch.autoconfigure.jdbc;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.context.properties.ConfigurationProperties;
 
 /**
@@ -31,12 +33,12 @@ public class JdbcBatchItemWriterProperties {
 	 * The name used to calculate the key within the
 	 * {@link org.springframework.batch.infrastructure.item.ExecutionContext}.
 	 */
-	private String name;
+	private @Nullable String name;
 
 	/**
 	 * The SQL statement to be used to update the database.
 	 */
-	private String sql;
+	private @Nullable String sql;
 
 	/**
 	 * If set to {@code true}, confirms that every insert results in the update of at
@@ -47,7 +49,7 @@ public class JdbcBatchItemWriterProperties {
 	/**
 	 * @return The current sql statement used to update the database.
 	 */
-	public String getSql() {
+	public @Nullable String getSql() {
 		return sql;
 	}
 
@@ -55,7 +57,7 @@ public String getSql() {
 	 * Sets the sql statement to be used to update the database.
 	 * @param sql the sql statement to be used.
 	 */
-	public void setSql(String sql) {
+	public void setSql(@Nullable String sql) {
 		this.sql = sql;
 	}
 
@@ -80,7 +82,7 @@ public void setAssertUpdates(boolean assertUpdates) {
 	 * keys.
 	 * @return the name
 	 */
-	public String getName() {
+	public @Nullable String getName() {
 		return name;
 	}
 
@@ -90,7 +92,7 @@ public String getName() {
 	 * @param name name of the writer instance
 	 * @see org.springframework.batch.infrastructure.item.ItemStreamSupport#setName(String)
 	 */
-	public void setName(String name) {
+	public void setName(@Nullable String name) {
 		this.name = name;
 	}
 
diff --git a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/jdbc/JdbcCursorItemReaderAutoConfiguration.java b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/jdbc/JdbcCursorItemReaderAutoConfiguration.java
index 64b8b3871..d1e74a88a 100644
--- a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/jdbc/JdbcCursorItemReaderAutoConfiguration.java
+++ b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/jdbc/JdbcCursorItemReaderAutoConfiguration.java
@@ -43,6 +43,7 @@
 import org.springframework.context.annotation.Import;
 import org.springframework.jdbc.core.PreparedStatementSetter;
 import org.springframework.jdbc.core.RowMapper;
+import org.springframework.util.Assert;
 
 /**
  * @author Michael Minella
@@ -84,6 +85,8 @@ public JdbcCursorItemReader<Map<String, Object>> itemReader(
 			logger.info("Using Default Data Source for the JdbcCursorItemReader");
 
 		}
+		Assert.state(this.properties.getSql() != null, "sql must not be null");
+		Assert.state(this.properties.getName() != null, "name must not be null");
 		return new JdbcCursorItemReaderBuilder<Map<String, Object>>().name(this.properties.getName())
 			.currentItemCount(this.properties.getCurrentItemCount())
 			.dataSource(readerDataSource)
diff --git a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/jdbc/JdbcCursorItemReaderProperties.java b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/jdbc/JdbcCursorItemReaderProperties.java
index f374c1361..d695b5132 100644
--- a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/jdbc/JdbcCursorItemReaderProperties.java
+++ b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/jdbc/JdbcCursorItemReaderProperties.java
@@ -16,6 +16,8 @@
 
 package org.springframework.cloud.task.batch.autoconfigure.jdbc;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.context.properties.ConfigurationProperties;
 
 /**
@@ -38,7 +40,7 @@ public class JdbcCursorItemReaderProperties {
 	 * Returns the configured value of the name used to calculate {@code ExecutionContext}
 	 * keys.
 	 */
-	private String name;
+	private @Nullable String name;
 
 	/**
 	 * Configure the maximum number of items to be read.
@@ -93,7 +95,7 @@ public class JdbcCursorItemReaderProperties {
 	/**
 	 * The SQL query to be executed.
 	 */
-	private String sql;
+	private @Nullable String sql;
 
 	/**
 	 * Returns the configured value of if the state of the reader will be persisted.
@@ -120,7 +122,7 @@ public void setSaveState(boolean saveState) {
 	 * keys.
 	 * @return the name
 	 */
-	public String getName() {
+	public @Nullable String getName() {
 		return this.name;
 	}
 
@@ -131,7 +133,7 @@ public String getName() {
 	 * @param name name of the reader instance
 	 * @see org.springframework.batch.infrastructure.item.ItemStreamSupport#setName(String)
 	 */
-	public void setName(String name) {
+	public void setName(@Nullable String name) {
 		this.name = name;
 	}
 
@@ -297,7 +299,7 @@ public void setUseSharedExtendedConnection(boolean useSharedExtendedConnection)
 	 * Returns the SQL query to be executed.
 	 * @return the SQL query
 	 */
-	public String getSql() {
+	public @Nullable String getSql() {
 		return sql;
 	}
 
@@ -306,7 +308,7 @@ public String getSql() {
 	 * @param sql the query
 	 * @see org.springframework.batch.infrastructure.item.database.builder.JdbcCursorItemReaderBuilder#sql(String)
 	 */
-	public void setSql(String sql) {
+	public void setSql(@Nullable String sql) {
 		this.sql = sql;
 	}
 
diff --git a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/jdbc/package-info.java b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/jdbc/package-info.java
index cfad96e8a..129832cfe 100644
--- a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/jdbc/package-info.java
+++ b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/jdbc/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Auto-configuration classes for JDBC item readers and writers in single-step batch jobs.
  */
+@NullMarked
 package org.springframework.cloud.task.batch.autoconfigure.jdbc;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/kafka/KafkaItemReaderAutoConfiguration.java b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/kafka/KafkaItemReaderAutoConfiguration.java
index 63aad9b48..420446dee 100644
--- a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/kafka/KafkaItemReaderAutoConfiguration.java
+++ b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/kafka/KafkaItemReaderAutoConfiguration.java
@@ -32,6 +32,7 @@
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.boot.kafka.autoconfigure.KafkaProperties;
 import org.springframework.context.annotation.Bean;
+import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
 /**
@@ -63,6 +64,8 @@ public KafkaItemReader<Object, Map<String, Object>> kafkaItemReader(
 			kafkaItemReaderProperties.setPartitions(new ArrayList<>(1));
 			kafkaItemReaderProperties.getPartitions().add(0);
 		}
+		Assert.state(kafkaItemReaderProperties.getName() != null, "name must not be null");
+		Assert.state(kafkaItemReaderProperties.getTopic() != null, "topic must not be null");
 		return new KafkaItemReaderBuilder<Object, Map<String, Object>>()
 			.partitions(kafkaItemReaderProperties.getPartitions())
 			.consumerProperties(consumerProperties)
diff --git a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/kafka/KafkaItemReaderProperties.java b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/kafka/KafkaItemReaderProperties.java
index d454318ce..a37c02a28 100644
--- a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/kafka/KafkaItemReaderProperties.java
+++ b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/kafka/KafkaItemReaderProperties.java
@@ -19,6 +19,8 @@
 import java.util.ArrayList;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.context.properties.ConfigurationProperties;
 
 /**
@@ -34,12 +36,12 @@ public class KafkaItemReaderProperties {
 	 * The name used to calculate the key within the
 	 * {@link org.springframework.batch.infrastructure.item.ExecutionContext}.
 	 */
-	private String name;
+	private @Nullable String name;
 
 	/**
 	 * The topic name from which the messages is read.
 	 */
-	private String topic;
+	private @Nullable String topic;
 
 	/**
 	 * A list of partitions to manually assign to the consumer. Defaults to a single entry
@@ -67,7 +69,7 @@ public class KafkaItemReaderProperties {
 	 * keys.
 	 * @return the name
 	 */
-	public String getName() {
+	public @Nullable String getName() {
 		return name;
 	}
 
@@ -77,7 +79,7 @@ public String getName() {
 	 * @param name name of the writer instance
 	 * @see org.springframework.batch.infrastructure.item.ItemStreamSupport#setName(String)
 	 */
-	public void setName(String name) {
+	public void setName(@Nullable String name) {
 		this.name = name;
 	}
 
@@ -85,7 +87,7 @@ public void setName(String name) {
 	 * Returns the name of the topic from which messages will be read.
 	 * @return the name of the topic.
 	 */
-	public String getTopic() {
+	public @Nullable String getTopic() {
 		return topic;
 	}
 
@@ -93,7 +95,7 @@ public String getTopic() {
 	 * The topic name from which the messages will be read.
 	 * @param topic name of the topic
 	 */
-	public void setTopic(String topic) {
+	public void setTopic(@Nullable String topic) {
 		this.topic = topic;
 	}
 
diff --git a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/kafka/KafkaItemWriterAutoConfiguration.java b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/kafka/KafkaItemWriterAutoConfiguration.java
index 3902f67ce..cb5e525a1 100644
--- a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/kafka/KafkaItemWriterAutoConfiguration.java
+++ b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/kafka/KafkaItemWriterAutoConfiguration.java
@@ -57,6 +57,7 @@ public class KafkaItemWriterAutoConfiguration {
 	@Bean
 	@ConditionalOnMissingBean
 	@ConditionalOnProperty(prefix = "spring.batch.job.kafkaitemwriter", name = "topic")
+	@SuppressWarnings("NullAway")
 	public KafkaItemWriter<Object, Map<String, Object>> kafkaItemWriter(
 			KafkaItemWriterProperties kafkaItemWriterProperties,
 			ProducerFactory<Object, Map<String, Object>> producerFactory,
diff --git a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/kafka/KafkaItemWriterProperties.java b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/kafka/KafkaItemWriterProperties.java
index fbc56af49..f7eb31002 100644
--- a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/kafka/KafkaItemWriterProperties.java
+++ b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/kafka/KafkaItemWriterProperties.java
@@ -16,6 +16,8 @@
 
 package org.springframework.cloud.task.batch.autoconfigure.kafka;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.context.properties.ConfigurationProperties;
 
 /**
@@ -30,7 +32,7 @@ public class KafkaItemWriterProperties {
 	/**
 	 * The topic name from which the messages are written.
 	 */
-	private String topic;
+	private @Nullable String topic;
 
 	/**
 	 * Indicate whether the items being passed to the writer are all to be sent as delete
@@ -42,7 +44,7 @@ public class KafkaItemWriterProperties {
 	 * Returns the name of the topic from which messages will be written.
 	 * @return the name of the topic.
 	 */
-	public String getTopic() {
+	public @Nullable String getTopic() {
 		return topic;
 	}
 
@@ -50,7 +52,7 @@ public String getTopic() {
 	 * The topic name from which the messages are written.
 	 * @param topic name of the topic
 	 */
-	public void setTopic(String topic) {
+	public void setTopic(@Nullable String topic) {
 		this.topic = topic;
 	}
 
diff --git a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/kafka/package-info.java b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/kafka/package-info.java
index 5e901448f..c86581f9c 100644
--- a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/kafka/package-info.java
+++ b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/kafka/package-info.java
@@ -18,4 +18,7 @@
  * Auto-configuration classes for Kafka item readers and writers in single-step batch
  * jobs.
  */
+@NullMarked
 package org.springframework.cloud.task.batch.autoconfigure.kafka;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/package-info.java b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/package-info.java
index a84256d25..95aab2d07 100644
--- a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/package-info.java
+++ b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Auto-configuration classes for Spring Cloud Task single-step batch jobs.
  */
+@NullMarked
 package org.springframework.cloud.task.batch.autoconfigure;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/rabbit/package-info.java b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/rabbit/package-info.java
index ba64194db..1674ca977 100644
--- a/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/rabbit/package-info.java
+++ b/spring-cloud-starter-single-step-batch-job/src/main/java/org/springframework/cloud/task/batch/autoconfigure/rabbit/package-info.java
@@ -18,4 +18,7 @@
  * Auto-configuration classes for RabbitMQ item readers and writers in single-step batch
  * jobs.
  */
+@NullMarked
 package org.springframework.cloud.task.batch.autoconfigure.rabbit;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/configuration/TaskBatchExecutionListenerFactoryBean.java b/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/configuration/TaskBatchExecutionListenerFactoryBean.java
index 83c96db1f..6bd2c59b4 100644
--- a/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/configuration/TaskBatchExecutionListenerFactoryBean.java
+++ b/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/configuration/TaskBatchExecutionListenerFactoryBean.java
@@ -20,6 +20,8 @@
 
 import javax.sql.DataSource;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.aop.framework.Advised;
 import org.springframework.aop.support.AopUtils;
 import org.springframework.beans.factory.FactoryBean;
@@ -42,9 +44,9 @@
  */
 public class TaskBatchExecutionListenerFactoryBean implements FactoryBean<TaskBatchExecutionListener> {
 
-	private TaskBatchExecutionListener listener;
+	private @Nullable TaskBatchExecutionListener listener;
 
-	private DataSource dataSource;
+	private @Nullable DataSource dataSource;
 
 	private TaskExplorer taskExplorer;
 
@@ -56,7 +58,7 @@ public class TaskBatchExecutionListenerFactoryBean implements FactoryBean<TaskBa
 	 * @param dataSource the dataSource to use for the TaskBatchExecutionListener.
 	 * @param taskExplorer the taskExplorer to use for the TaskBatchExecutionListener.
 	 */
-	public TaskBatchExecutionListenerFactoryBean(DataSource dataSource, TaskExplorer taskExplorer) {
+	public TaskBatchExecutionListenerFactoryBean(@Nullable DataSource dataSource, TaskExplorer taskExplorer) {
 		this.dataSource = dataSource;
 		this.taskExplorer = taskExplorer;
 	}
@@ -68,7 +70,8 @@ public TaskBatchExecutionListenerFactoryBean(DataSource dataSource, TaskExplorer
 	 * @param tablePrefix the prefix for the task tables accessed by the
 	 * TaskBatchExecutionListener.
 	 */
-	public TaskBatchExecutionListenerFactoryBean(DataSource dataSource, TaskExplorer taskExplorer, String tablePrefix) {
+	public TaskBatchExecutionListenerFactoryBean(@Nullable DataSource dataSource, TaskExplorer taskExplorer,
+			String tablePrefix) {
 		this(dataSource, taskExplorer);
 		Assert.hasText(tablePrefix, "tablePrefix must not be null nor empty.");
 		this.tablePrefix = tablePrefix;
@@ -101,6 +104,7 @@ public boolean isSingleton() {
 
 	private MapTaskBatchDao getMapTaskBatchDao() throws Exception {
 		Field taskExecutionDaoField = ReflectionUtils.findField(SimpleTaskExplorer.class, "taskExecutionDao");
+		Assert.state(taskExecutionDaoField != null, "taskExecutionDao field must exist in SimpleTaskExplorer");
 		taskExecutionDaoField.setAccessible(true);
 
 		MapTaskExecutionDao taskExecutionDao;
@@ -117,6 +121,7 @@ private MapTaskBatchDao getMapTaskBatchDao() throws Exception {
 			taskExecutionDao = (MapTaskExecutionDao) ReflectionUtils.getField(taskExecutionDaoField, this.taskExplorer);
 		}
 
+		Assert.state(taskExecutionDao != null, "taskExecutionDao must not be null");
 		return new MapTaskBatchDao(taskExecutionDao.getBatchJobAssociations());
 	}
 
diff --git a/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/configuration/TaskJobLauncherApplicationRunnerFactoryBean.java b/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/configuration/TaskJobLauncherApplicationRunnerFactoryBean.java
index 232e3c15c..6e2c404f9 100644
--- a/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/configuration/TaskJobLauncherApplicationRunnerFactoryBean.java
+++ b/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/configuration/TaskJobLauncherApplicationRunnerFactoryBean.java
@@ -53,6 +53,7 @@ public class TaskJobLauncherApplicationRunnerFactoryBean
 
 	private final JobRepository jobRepository;
 
+	@SuppressWarnings("NullAway.Init")
 	private ApplicationEventPublisher applicationEventPublisher;
 
 	public TaskJobLauncherApplicationRunnerFactoryBean(JobOperator jobOperator, List<Job> jobs,
diff --git a/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/configuration/package-info.java b/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/configuration/package-info.java
index c41ff1e43..6fdd602c8 100644
--- a/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/configuration/package-info.java
+++ b/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/configuration/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Configuration classes for Spring Cloud Task Batch integration.
  */
+@NullMarked
 package org.springframework.cloud.task.batch.configuration;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/handler/TaskJobLauncherApplicationRunner.java b/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/handler/TaskJobLauncherApplicationRunner.java
index 3be76f00f..1bc894d0d 100644
--- a/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/handler/TaskJobLauncherApplicationRunner.java
+++ b/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/handler/TaskJobLauncherApplicationRunner.java
@@ -28,6 +28,7 @@
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.batch.core.BatchStatus;
 import org.springframework.batch.core.job.Job;
@@ -79,7 +80,7 @@ public class TaskJobLauncherApplicationRunner extends JobLauncherApplicationRunn
 
 	private final List<JobExecution> jobExecutionList = new ArrayList<>();
 
-	private ApplicationEventPublisher taskApplicationEventPublisher;
+	private @Nullable ApplicationEventPublisher taskApplicationEventPublisher;
 
 	private final TaskBatchProperties taskBatchProperties;
 
@@ -183,7 +184,10 @@ private void monitorJobExecutions() {
 
 	private BatchStatus getCurrentBatchStatus(JobExecution jobExecution) {
 		if (jobExecution.getStatus().isRunning()) {
-			return this.taskJobRepository.getJobExecution(jobExecution.getId()).getStatus();
+			JobExecution jobExecutionWithStatus = this.taskJobRepository.getJobExecution(jobExecution.getId());
+			Assert.state(jobExecutionWithStatus != null,
+					"Job execution with id " + jobExecution.getId() + " not found");
+			return jobExecutionWithStatus.getStatus();
 		}
 		return jobExecution.getStatus();
 	}
diff --git a/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/handler/package-info.java b/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/handler/package-info.java
index 743bd94a6..2676f813b 100644
--- a/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/handler/package-info.java
+++ b/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/handler/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Handler components for Spring Cloud Task Batch integration.
  */
+@NullMarked
 package org.springframework.cloud.task.batch.handler;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/listener/TaskBatchExecutionListener.java b/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/listener/TaskBatchExecutionListener.java
index 9d7c1a726..5ecce2c16 100644
--- a/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/listener/TaskBatchExecutionListener.java
+++ b/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/listener/TaskBatchExecutionListener.java
@@ -36,6 +36,7 @@ public class TaskBatchExecutionListener implements JobExecutionListener, Ordered
 
 	private static final Log logger = LogFactory.getLog(TaskBatchExecutionListener.class);
 
+	@SuppressWarnings("NullAway.Init")
 	private TaskExecution taskExecution;
 
 	private final TaskBatchDao taskBatchDao;
diff --git a/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/listener/package-info.java b/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/listener/package-info.java
index ff0009bf9..adeb17b22 100644
--- a/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/listener/package-info.java
+++ b/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/listener/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Listener components for Spring Cloud Task Batch integration.
  */
+@NullMarked
 package org.springframework.cloud.task.batch.listener;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/listener/support/package-info.java b/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/listener/support/package-info.java
index c9584bcab..3e0f6d258 100644
--- a/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/listener/support/package-info.java
+++ b/spring-cloud-task-batch/src/main/java/org/springframework/cloud/task/batch/listener/support/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Support classes for Spring Cloud Task Batch listener implementations.
  */
+@NullMarked
 package org.springframework.cloud.task.batch.listener.support;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/DefaultTaskConfigurer.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/DefaultTaskConfigurer.java
index dda852976..dcd189d15 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/DefaultTaskConfigurer.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/DefaultTaskConfigurer.java
@@ -21,6 +21,7 @@
 import jakarta.persistence.EntityManager;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.batch.infrastructure.support.transaction.ResourcelessTransactionManager;
 import org.springframework.cloud.task.repository.TaskExplorer;
@@ -36,6 +37,7 @@
 import org.springframework.jdbc.support.JdbcTransactionManager;
 import org.springframework.orm.jpa.JpaTransactionManager;
 import org.springframework.transaction.PlatformTransactionManager;
+import org.springframework.util.Assert;
 
 /**
  * Default implementation of the TaskConfigurer interface. If no {@link TaskConfigurer}
@@ -56,17 +58,17 @@ public class DefaultTaskConfigurer implements TaskConfigurer {
 
 	private static final Log logger = LogFactory.getLog(DefaultTaskConfigurer.class);
 
-	private TaskProperties taskProperties;
+	private @Nullable TaskProperties taskProperties;
 
 	private TaskRepository taskRepository;
 
 	private TaskExplorer taskExplorer;
 
-	private PlatformTransactionManager transactionManager;
+	private @Nullable PlatformTransactionManager transactionManager;
 
-	private DataSource dataSource;
+	private @Nullable DataSource dataSource;
 
-	private ApplicationContext context;
+	private @Nullable ApplicationContext context;
 
 	public DefaultTaskConfigurer() {
 		this(TaskProperties.DEFAULT_TABLE_PREFIX);
@@ -87,7 +89,7 @@ public DefaultTaskConfigurer(TaskProperties taskProperties) {
 	 * repository. If none is provided, a Map will be used (not recommended for production
 	 * use).
 	 */
-	public DefaultTaskConfigurer(DataSource dataSource) {
+	public DefaultTaskConfigurer(@Nullable DataSource dataSource) {
 		this(dataSource, TaskProperties.DEFAULT_TABLE_PREFIX, null);
 	}
 
@@ -100,7 +102,7 @@ public DefaultTaskConfigurer(DataSource dataSource) {
 	 * @param taskProperties the task properties used to obtain tablePrefix if not set by
 	 * tablePrefix field.
 	 */
-	public DefaultTaskConfigurer(DataSource dataSource, TaskProperties taskProperties) {
+	public DefaultTaskConfigurer(@Nullable DataSource dataSource, TaskProperties taskProperties) {
 		this(dataSource, null, null, taskProperties);
 	}
 
@@ -109,7 +111,7 @@ public DefaultTaskConfigurer(DataSource dataSource, TaskProperties taskPropertie
 	 * @param tablePrefix the prefix to apply to the task table names used by task
 	 * infrastructure.
 	 */
-	public DefaultTaskConfigurer(String tablePrefix) {
+	public DefaultTaskConfigurer(@Nullable String tablePrefix) {
 		this(null, tablePrefix, null);
 	}
 
@@ -120,7 +122,7 @@ public DefaultTaskConfigurer(String tablePrefix) {
 	 * @param taskProperties the task properties used to obtain tablePrefix if not set by
 	 * tablePrefix field.
 	 */
-	public DefaultTaskConfigurer(String tablePrefix, TaskProperties taskProperties) {
+	public DefaultTaskConfigurer(@Nullable String tablePrefix, TaskProperties taskProperties) {
 		this(null, tablePrefix, null, taskProperties);
 	}
 
@@ -133,7 +135,8 @@ public DefaultTaskConfigurer(String tablePrefix, TaskProperties taskProperties)
 	 * infrastructure.
 	 * @param context the context to be used.
 	 */
-	public DefaultTaskConfigurer(DataSource dataSource, String tablePrefix, ApplicationContext context) {
+	public DefaultTaskConfigurer(@Nullable DataSource dataSource, @Nullable String tablePrefix,
+			@Nullable ApplicationContext context) {
 		this(dataSource, tablePrefix, context, null);
 	}
 
@@ -148,8 +151,8 @@ public DefaultTaskConfigurer(DataSource dataSource, String tablePrefix, Applicat
 	 * @param taskProperties the task properties used to obtain tablePrefix if not set by
 	 * tablePrefix field.
 	 */
-	public DefaultTaskConfigurer(DataSource dataSource, String tablePrefix, ApplicationContext context,
-			TaskProperties taskProperties) {
+	public DefaultTaskConfigurer(@Nullable DataSource dataSource, @Nullable String tablePrefix,
+			@Nullable ApplicationContext context, @Nullable TaskProperties taskProperties) {
 		this.dataSource = dataSource;
 		this.context = context;
 
@@ -183,7 +186,7 @@ public TaskExplorer getTaskExplorer() {
 	}
 
 	@Override
-	public DataSource getTaskDataSource() {
+	public @Nullable DataSource getTaskDataSource() {
 		return this.dataSource;
 	}
 
@@ -208,6 +211,7 @@ public PlatformTransactionManager getTransactionManager() {
 				}
 				finally {
 					if (this.transactionManager == null) {
+						Assert.state(this.dataSource != null, "DataSource must be non-null when available");
 						this.transactionManager = new JdbcTransactionManager(this.dataSource);
 					}
 				}
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/SimpleTaskAutoConfiguration.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/SimpleTaskAutoConfiguration.java
index 91a3f9859..c87d74566 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/SimpleTaskAutoConfiguration.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/SimpleTaskAutoConfiguration.java
@@ -24,6 +24,7 @@
 import jakarta.annotation.PostConstruct;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.aop.scope.ScopedProxyUtils;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -43,6 +44,7 @@
 import org.springframework.context.annotation.Profile;
 import org.springframework.transaction.PlatformTransactionManager;
 import org.springframework.transaction.annotation.EnableTransactionManagement;
+import org.springframework.util.Assert;
 import org.springframework.util.CollectionUtils;
 
 /**
@@ -67,7 +69,7 @@ public class SimpleTaskAutoConfiguration {
 	protected static final Log logger = LogFactory.getLog(SimpleTaskAutoConfiguration.class);
 
 	@Autowired(required = false)
-	private Collection<DataSource> dataSources;
+	private @Nullable Collection<DataSource> dataSources;
 
 	@Autowired
 	private ConfigurableApplicationContext context;
@@ -77,33 +79,37 @@ public class SimpleTaskAutoConfiguration {
 
 	private boolean initialized = false;
 
-	private TaskRepository taskRepository;
+	private @Nullable TaskRepository taskRepository;
 
-	private PlatformTransactionManager platformTransactionManager;
+	private @Nullable PlatformTransactionManager platformTransactionManager;
 
-	private TaskExplorer taskExplorer;
+	private @Nullable TaskExplorer taskExplorer;
 
-	private TaskNameResolver taskNameResolver;
+	private @Nullable TaskNameResolver taskNameResolver;
 
 	@Bean
 	public SimpleTaskRepository taskRepository() {
+		Assert.state(this.taskRepository != null, "taskRepository must be initialized");
 		return (SimpleTaskRepository) this.taskRepository;
 	}
 
 	@Conditional(NoTransactionManagerProperty.class)
 	@Bean
 	public PlatformTransactionManager springCloudTaskTransactionManager() {
+		Assert.state(this.platformTransactionManager != null, "platformTransactionManager must be initialized");
 		return this.platformTransactionManager;
 	}
 
 	@Bean
 	public TaskExplorer taskExplorer() {
+		Assert.state(this.taskExplorer != null, "taskExplorer must be initialized");
 		return this.taskExplorer;
 	}
 
 	@Bean
 	public TaskNameResolver taskNameResolver() {
-		return taskNameResolver;
+		Assert.state(this.taskNameResolver != null, "taskNameResolver must be initialized");
+		return this.taskNameResolver;
 	}
 
 	@Bean
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/SingleInstanceTaskListener.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/SingleInstanceTaskListener.java
index 9aa7d2374..5f6fa7d61 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/SingleInstanceTaskListener.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/SingleInstanceTaskListener.java
@@ -22,6 +22,7 @@
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.cloud.task.listener.TaskExecutionException;
 import org.springframework.cloud.task.listener.annotation.AfterTask;
@@ -41,6 +42,7 @@
 import org.springframework.integration.support.leader.LockRegistryLeaderInitiator;
 import org.springframework.integration.support.locks.LockRegistry;
 import org.springframework.transaction.PlatformTransactionManager;
+import org.springframework.util.Assert;
 
 /**
  * When spring.cloud.task.single-instance-enabled is set to true this listener will create
@@ -56,9 +58,10 @@ public class SingleInstanceTaskListener implements ApplicationListener<Applicati
 
 	private static final Log logger = LogFactory.getLog(SingleInstanceTaskListener.class);
 
+	@SuppressWarnings("NullAway.Init")
 	private LockRegistry lockRegistry;
 
-	private LockRegistryLeaderInitiator lockRegistryLeaderInitiator;
+	private @Nullable LockRegistryLeaderInitiator lockRegistryLeaderInitiator;
 
 	private TaskNameResolver taskNameResolver;
 
@@ -68,12 +71,14 @@ public class SingleInstanceTaskListener implements ApplicationListener<Applicati
 
 	private boolean lockFailed;
 
+	@SuppressWarnings("NullAway.Init")
 	private DataSource dataSource;
 
 	private TaskProperties taskProperties;
 
 	private ApplicationContext applicationContext;
 
+	@SuppressWarnings("NullAway.Init")
 	private PlatformTransactionManager platformTransactionManager;
 
 	public SingleInstanceTaskListener(LockRegistry lockRegistry, TaskNameResolver taskNameResolver,
@@ -104,8 +109,10 @@ public void lockTask(TaskExecution taskExecution) {
 		if (this.lockRegistry == null) {
 			this.lockRegistry = getDefaultLockRegistry(taskExecution.getExecutionId());
 		}
-		this.lockRegistryLeaderInitiator = new LockRegistryLeaderInitiator(this.lockRegistry, new DefaultCandidate(
-				String.valueOf(taskExecution.getExecutionId()), this.taskNameResolver.getTaskName()));
+		String taskName = this.taskNameResolver.getTaskName();
+		Assert.state(taskName != null, "No task name available");
+		this.lockRegistryLeaderInitiator = new LockRegistryLeaderInitiator(this.lockRegistry,
+				new DefaultCandidate(String.valueOf(taskExecution.getExecutionId()), taskName));
 		this.lockRegistryLeaderInitiator.setApplicationEventPublisher(this.applicationEventPublisher);
 		this.lockRegistryLeaderInitiator.setPublishFailedEvents(true);
 		this.lockRegistryLeaderInitiator.start();
@@ -132,12 +139,16 @@ public void lockTask(TaskExecution taskExecution) {
 
 	@AfterTask
 	public void unlockTaskOnEnd(TaskExecution taskExecution) throws Exception {
-		this.lockRegistryLeaderInitiator.destroy();
+		if (this.lockRegistryLeaderInitiator != null) {
+			this.lockRegistryLeaderInitiator.destroy();
+		}
 	}
 
 	@FailedTask
 	public void unlockTaskOnError(TaskExecution taskExecution, Throwable throwable) throws Exception {
-		this.lockRegistryLeaderInitiator.destroy();
+		if (this.lockRegistryLeaderInitiator != null) {
+			this.lockRegistryLeaderInitiator.destroy();
+		}
 	}
 
 	@Override
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/TaskConfigurer.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/TaskConfigurer.java
index 061d6cfd8..40676c017 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/TaskConfigurer.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/TaskConfigurer.java
@@ -18,6 +18,8 @@
 
 import javax.sql.DataSource;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.cloud.task.repository.TaskExplorer;
 import org.springframework.cloud.task.repository.TaskNameResolver;
 import org.springframework.cloud.task.repository.TaskRepository;
@@ -57,6 +59,7 @@ public interface TaskConfigurer {
 	 * return null.
 	 * @return {@link DataSource} that will be used for task operations.
 	 */
+	@Nullable
 	DataSource getTaskDataSource();
 
 	/**
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/TaskLifecycleConfiguration.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/TaskLifecycleConfiguration.java
index 31037f64c..ff453c012 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/TaskLifecycleConfiguration.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/TaskLifecycleConfiguration.java
@@ -49,6 +49,7 @@ public class TaskLifecycleConfiguration {
 
 	private ConfigurableApplicationContext context;
 
+	@SuppressWarnings("NullAway.Init")
 	private ApplicationArguments applicationArguments;
 
 	private TaskRepository taskRepository;
@@ -57,6 +58,7 @@ public class TaskLifecycleConfiguration {
 
 	private TaskNameResolver taskNameResolver;
 
+	@SuppressWarnings("NullAway.Init")
 	private TaskLifecycleListener taskLifecycleListener;
 
 	private boolean initialized = false;
@@ -65,6 +67,7 @@ public class TaskLifecycleConfiguration {
 
 	private TaskObservationCloudKeyValues taskObservationCloudKeyValues;
 
+	@SuppressWarnings("NullAway")
 	@Autowired
 	public TaskLifecycleConfiguration(TaskProperties taskProperties, ConfigurableApplicationContext context,
 			TaskRepository taskRepository, TaskExplorer taskExplorer, TaskNameResolver taskNameResolver,
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/TaskObservationCloudKeyValues.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/TaskObservationCloudKeyValues.java
index 27b1a051e..e2244bc90 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/TaskObservationCloudKeyValues.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/TaskObservationCloudKeyValues.java
@@ -27,24 +27,31 @@
  */
 public class TaskObservationCloudKeyValues {
 
+	@SuppressWarnings("NullAway.Init")
 	@Value("${vcap.application.org_name:default}")
 	private String organizationName;
 
+	@SuppressWarnings("NullAway.Init")
 	@Value("${vcap.application.space_id:unknown}")
 	private String spaceId;
 
+	@SuppressWarnings("NullAway.Init")
 	@Value("${vcap.application.space_name:unknown}")
 	private String spaceName;
 
+	@SuppressWarnings("NullAway.Init")
 	@Value("${vcap.application.application_name:unknown}")
 	private String applicationName;
 
+	@SuppressWarnings("NullAway.Init")
 	@Value("${vcap.application.application_id:unknown}")
 	private String applicationId;
 
+	@SuppressWarnings("NullAway.Init")
 	@Value("${vcap.application.application_version:unknown}")
 	private String applicationVersion;
 
+	@SuppressWarnings("NullAway.Init")
 	@Value("${vcap.application.instance_index:0}")
 	private String instanceIndex;
 
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/TaskProperties.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/TaskProperties.java
index f11ec29f7..87205bc90 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/TaskProperties.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/TaskProperties.java
@@ -18,6 +18,7 @@
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.boot.context.properties.ConfigurationProperties;
 
@@ -43,18 +44,18 @@ public class TaskProperties {
 	/**
 	 * An id that can be associated with a task.
 	 */
-	private String externalExecutionId;
+	private @Nullable String externalExecutionId;
 
 	/**
 	 * An id that will be used by the task when updating the task execution.
 	 */
-	private Long executionid;
+	private @Nullable Long executionid;
 
 	/**
 	 * The id of the parent task execution id that launched this task execution. Defaults
 	 * to null if task execution had no parent.
 	 */
-	private Long parentExecutionId;
+	private @Nullable Long parentExecutionId;
 
 	/**
 	 * The prefix to append to the table names created by Spring Cloud Task.
@@ -94,21 +95,21 @@ public class TaskProperties {
 	 * that we can support the <code>spring.cloud.task.initialize.enable</code> until it
 	 * is removed.
 	 */
-	private Boolean initializeEnabled;
+	private @Nullable Boolean initializeEnabled;
 
-	public String getExternalExecutionId() {
+	public @Nullable String getExternalExecutionId() {
 		return this.externalExecutionId;
 	}
 
-	public void setExternalExecutionId(String externalExecutionId) {
+	public void setExternalExecutionId(@Nullable String externalExecutionId) {
 		this.externalExecutionId = externalExecutionId;
 	}
 
-	public Long getExecutionid() {
+	public @Nullable Long getExecutionid() {
 		return this.executionid;
 	}
 
-	public void setExecutionid(Long executionid) {
+	public void setExecutionid(@Nullable Long executionid) {
 		this.executionid = executionid;
 	}
 
@@ -128,11 +129,11 @@ public void setTablePrefix(String tablePrefix) {
 		this.tablePrefix = tablePrefix;
 	}
 
-	public Long getParentExecutionId() {
+	public @Nullable Long getParentExecutionId() {
 		return this.parentExecutionId;
 	}
 
-	public void setParentExecutionId(Long parentExecutionId) {
+	public void setParentExecutionId(@Nullable Long parentExecutionId) {
 		this.parentExecutionId = parentExecutionId;
 	}
 
@@ -160,11 +161,11 @@ public void setSingleInstanceLockCheckInterval(int singleInstanceLockCheckInterv
 		this.singleInstanceLockCheckInterval = singleInstanceLockCheckInterval;
 	}
 
-	public Boolean isInitializeEnabled() {
-		return initializeEnabled;
+	public @Nullable Boolean isInitializeEnabled() {
+		return this.initializeEnabled;
 	}
 
-	public void setInitializeEnabled(Boolean initializeEnabled) {
+	public void setInitializeEnabled(@Nullable Boolean initializeEnabled) {
 		this.initializeEnabled = initializeEnabled;
 	}
 
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/TaskRuntimeHints.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/TaskRuntimeHints.java
index 071ea19aa..c194712e2 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/TaskRuntimeHints.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/TaskRuntimeHints.java
@@ -18,6 +18,8 @@
 
 import java.sql.Statement;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.aot.hint.MemberCategory;
 import org.springframework.aot.hint.RuntimeHints;
 import org.springframework.aot.hint.RuntimeHintsRegistrar;
@@ -34,7 +36,7 @@
 public class TaskRuntimeHints implements RuntimeHintsRegistrar {
 
 	@Override
-	public void registerHints(RuntimeHints hints, ClassLoader classLoader) {
+	public void registerHints(RuntimeHints hints, @Nullable ClassLoader classLoader) {
 		hints.reflection().registerType(TypeReference.of("java.sql.DatabaseMetaData"), hint -> {
 		});
 		hints.resources().registerPattern("org/springframework/cloud/task/schema-db2.sql");
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/observation/ObservationApplicationRunner.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/observation/ObservationApplicationRunner.java
index c9997ffad..bc95b43c3 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/observation/ObservationApplicationRunner.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/observation/ObservationApplicationRunner.java
@@ -18,6 +18,7 @@
 
 import io.micrometer.observation.Observation;
 import io.micrometer.observation.ObservationRegistry;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.boot.ApplicationArguments;
@@ -38,9 +39,9 @@ class ObservationApplicationRunner implements ApplicationRunner {
 
 	private final String beanName;
 
-	private ObservationRegistry registry;
+	private @Nullable ObservationRegistry registry;
 
-	private TaskObservationConvention taskObservationConvention;
+	private @Nullable TaskObservationConvention taskObservationConvention;
 
 	ObservationApplicationRunner(BeanFactory beanFactory, ApplicationRunner delegate, String beanName) {
 		this.beanFactory = beanFactory;
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/observation/ObservationCommandLineRunner.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/observation/ObservationCommandLineRunner.java
index 299bef854..97811159b 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/observation/ObservationCommandLineRunner.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/observation/ObservationCommandLineRunner.java
@@ -18,6 +18,7 @@
 
 import io.micrometer.observation.Observation;
 import io.micrometer.observation.ObservationRegistry;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.boot.CommandLineRunner;
@@ -37,9 +38,9 @@ class ObservationCommandLineRunner implements CommandLineRunner {
 
 	private final String beanName;
 
-	private ObservationRegistry registry;
+	private @Nullable ObservationRegistry registry;
 
-	private TaskObservationConvention taskObservationConvention;
+	private @Nullable TaskObservationConvention taskObservationConvention;
 
 	ObservationCommandLineRunner(BeanFactory beanFactory, CommandLineRunner delegate, String beanName) {
 		this.beanFactory = beanFactory;
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/observation/package-info.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/observation/package-info.java
index df72d6209..0b9974d16 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/observation/package-info.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/observation/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Observation support for Spring Cloud Task configuration.
  */
+@NullMarked
 package org.springframework.cloud.task.configuration.observation;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/package-info.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/package-info.java
index 1c8584b59..09340143a 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/package-info.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/configuration/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Interfaces for configuring Spring Cloud Task and a default implementations.
  */
+@NullMarked
 package org.springframework.cloud.task.configuration;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/TaskLifecycleListener.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/TaskLifecycleListener.java
index 39c1759ba..b9b7bdf57 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/TaskLifecycleListener.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/TaskLifecycleListener.java
@@ -30,6 +30,7 @@
 import io.micrometer.observation.ObservationRegistry;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -102,8 +103,9 @@ public class TaskLifecycleListener
 	@Autowired(required = false)
 	private ObservationConvention observationConvention;
 
-	private List<TaskExecutionListener> taskExecutionListeners;
+	private @Nullable List<TaskExecutionListener> taskExecutionListeners;
 
+	@SuppressWarnings("NullAway.Init")
 	private TaskExecution taskExecution;
 
 	private TaskProperties taskProperties;
@@ -114,15 +116,15 @@ public class TaskLifecycleListener
 
 	private boolean listenerFailed = false;
 
-	private Throwable listenerException;
+	private @Nullable Throwable listenerException;
 
-	private TaskNameResolver taskNameResolver;
+	private final TaskNameResolver taskNameResolver;
 
-	private ApplicationArguments applicationArguments;
+	private final ApplicationArguments applicationArguments;
 
-	private Throwable applicationFailedException;
+	private @Nullable Throwable applicationFailedException;
 
-	private ExitCodeEvent exitCodeEvent;
+	private @Nullable ExitCodeEvent exitCodeEvent;
 
 	/**
 	 * @param taskRepository {@link TaskRepository} to record executions.
@@ -203,8 +205,11 @@ private void doTaskEnd() {
 			}
 
 			setExitMessage(invokeOnTaskEnd(this.taskExecution));
-			this.taskRepository.completeTaskExecution(this.taskExecution.getExecutionId(),
-					this.taskExecution.getExitCode(), this.taskExecution.getEndTime(),
+			Integer exitCode = this.taskExecution.getExitCode();
+			LocalDateTime endTime = this.taskExecution.getEndTime();
+			Assert.state(exitCode != null, "exitCode must not be null");
+			Assert.state(endTime != null, "endTime must not be null");
+			this.taskRepository.completeTaskExecution(this.taskExecution.getExecutionId(), exitCode, endTime,
 					this.taskExecution.getExitMessage(), this.taskExecution.getErrorMessage());
 
 			this.finished = true;
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/TaskListenerExecutorObjectFactory.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/TaskListenerExecutorObjectFactory.java
index 633e2694a..e4f40d1ac 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/TaskListenerExecutorObjectFactory.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/TaskListenerExecutorObjectFactory.java
@@ -57,10 +57,13 @@ public class TaskListenerExecutorObjectFactory implements ObjectFactory<TaskExec
 
 	private ConfigurableApplicationContext context;
 
+	@SuppressWarnings("NullAway.Init")
 	private Map<Method, Set<Object>> beforeTaskInstances;
 
+	@SuppressWarnings("NullAway.Init")
 	private Map<Method, Set<Object>> afterTaskInstances;
 
+	@SuppressWarnings("NullAway.Init")
 	private Map<Method, Set<Object>> failedTaskInstances;
 
 	public TaskListenerExecutorObjectFactory(ConfigurableApplicationContext context) {
@@ -76,6 +79,7 @@ public TaskListenerExecutor getObject() {
 		return new TaskListenerExecutor(this.beforeTaskInstances, this.afterTaskInstances, this.failedTaskInstances);
 	}
 
+	@SuppressWarnings("NullAway")
 	private void initializeExecutor() {
 		ConfigurableListableBeanFactory factory = this.context.getBeanFactory();
 		for (String beanName : this.context.getBeanDefinitionNames()) {
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/TaskObservations.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/TaskObservations.java
index cc95ef2df..db07401bb 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/TaskObservations.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/TaskObservations.java
@@ -19,6 +19,7 @@
 import io.micrometer.observation.Observation;
 import io.micrometer.observation.ObservationConvention;
 import io.micrometer.observation.ObservationRegistry;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.cloud.task.configuration.TaskObservationCloudKeyValues;
 import org.springframework.cloud.task.repository.TaskExecution;
@@ -60,12 +61,16 @@ public TaskObservations(ObservationRegistry observationRegistry,
 		this.customObservationConvention = customObservationConvention;
 	}
 
+	@SuppressWarnings("NullAway.Init")
 	private Observation.Scope scope;
 
+	@SuppressWarnings("NullAway.Init")
 	private TaskExecutionObservationConvention observationsProvider = new DefaultTaskExecutionObservationConvention();
 
+	@SuppressWarnings("NullAway.Init")
 	private TaskExecutionObservationContext taskObservationContext;
 
+	@Nullable
 	TaskObservationCloudKeyValues taskObservationCloudKeyValues;
 
 	public void onTaskStartup(TaskExecution taskExecution) {
@@ -107,7 +112,7 @@ public void onTaskStartup(TaskExecution taskExecution) {
 		this.scope = observation.openScope();
 	}
 
-	private String getValueOrDefault(Object value) {
+	private String getValueOrDefault(@Nullable Object value) {
 		return (value != null) ? value.toString() : UNKNOWN;
 	}
 
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/annotation/TaskListenerExecutor.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/annotation/TaskListenerExecutor.java
index 811712dfb..9cebdbfca 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/annotation/TaskListenerExecutor.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/annotation/TaskListenerExecutor.java
@@ -81,7 +81,9 @@ public void onTaskFailed(TaskExecution taskExecution, Throwable throwable) {
 	private void executeTaskListener(TaskExecution taskExecution, Set<Method> methods,
 			Map<Method, Set<Object>> instances) {
 		for (Method method : methods) {
-			for (Object instance : instances.get(method)) {
+			Set<Object> instanceSet = instances.get(method);
+			org.springframework.util.Assert.state(instanceSet != null, "instanceSet must not be null");
+			for (Object instance : instanceSet) {
 				try {
 					method.invoke(instance, taskExecution);
 				}
@@ -106,7 +108,9 @@ private void executeTaskListener(TaskExecution taskExecution, Set<Method> method
 	private void executeTaskListenerWithThrowable(TaskExecution taskExecution, Throwable throwable, Set<Method> methods,
 			Map<Method, Set<Object>> instances) {
 		for (Method method : methods) {
-			for (Object instance : instances.get(method)) {
+			Set<Object> instanceSet = instances.get(method);
+			org.springframework.util.Assert.state(instanceSet != null, "instanceSet must not be null");
+			for (Object instance : instanceSet) {
 				try {
 					method.invoke(instance, taskExecution, throwable);
 				}
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/annotation/package-info.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/annotation/package-info.java
index 1cc3ced7b..0ac78c375 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/annotation/package-info.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/annotation/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Annotation-based listener support for Spring Cloud Task.
  */
+@NullMarked
 package org.springframework.cloud.task.listener.annotation;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/package-info.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/package-info.java
index c91d25d4e..ae48eb2dd 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/package-info.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/listener/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Task lifecycle listener support for Spring Cloud Task.
  */
+@NullMarked
 package org.springframework.cloud.task.listener;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/package-info.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/package-info.java
index 45292b91f..fc6db9541 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/package-info.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Base package for spring cloud task.
  */
+@NullMarked
 package org.springframework.cloud.task;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/TaskExecution.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/TaskExecution.java
index ec032825b..c80b45ece 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/TaskExecution.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/TaskExecution.java
@@ -20,6 +20,8 @@
 import java.util.ArrayList;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.util.Assert;
 
 /**
@@ -40,46 +42,46 @@ public class TaskExecution {
 	/**
 	 * The parent task execution id.
 	 */
-	private Long parentExecutionId;
+	private @Nullable Long parentExecutionId;
 
 	/**
 	 * The recorded exit code for the task.
 	 */
-	private Integer exitCode;
+	private @Nullable Integer exitCode;
 
 	/**
 	 * User defined name for the task.
 	 */
-	private String taskName;
+	private @Nullable String taskName;
 
 	/**
 	 * Time of when the task was started.
 	 */
-	private LocalDateTime startTime;
+	private @Nullable LocalDateTime startTime;
 
 	/**
 	 * Timestamp of when the task was completed/terminated.
 	 */
-	private LocalDateTime endTime;
+	private @Nullable LocalDateTime endTime;
 
 	/**
 	 * Message returned from the task or stacktrace.
 	 */
-	private String exitMessage;
+	private @Nullable String exitMessage;
 
 	/**
 	 * Id assigned to the task by the platform.
 	 *
 	 * @since 1.1.0
 	 */
-	private String externalExecutionId;
+	private @Nullable String externalExecutionId;
 
 	/**
 	 * Error information available upon the failure of a task.
 	 *
 	 * @since 1.1.0
 	 */
-	private String errorMessage;
+	private @Nullable String errorMessage;
 
 	/**
 	 * The arguments that were used for this task execution.
@@ -90,9 +92,10 @@ public TaskExecution() {
 		this.arguments = new ArrayList<>();
 	}
 
-	public TaskExecution(long executionId, Integer exitCode, String taskName, LocalDateTime startTime,
-			LocalDateTime endTime, String exitMessage, List<String> arguments, String errorMessage,
-			String externalExecutionId, Long parentExecutionId) {
+	public TaskExecution(long executionId, @Nullable Integer exitCode, @Nullable String taskName,
+			@Nullable LocalDateTime startTime, @Nullable LocalDateTime endTime, @Nullable String exitMessage,
+			List<String> arguments, @Nullable String errorMessage, @Nullable String externalExecutionId,
+			@Nullable Long parentExecutionId) {
 
 		Assert.notNull(arguments, "arguments must not be null");
 		this.executionId = executionId;
@@ -107,9 +110,9 @@ public TaskExecution(long executionId, Integer exitCode, String taskName, LocalD
 		this.parentExecutionId = parentExecutionId;
 	}
 
-	public TaskExecution(long executionId, Integer exitCode, String taskName, LocalDateTime startTime,
-			LocalDateTime endTime, String exitMessage, List<String> arguments, String errorMessage,
-			String externalExecutionId) {
+	public TaskExecution(long executionId, @Nullable Integer exitCode, @Nullable String taskName,
+			@Nullable LocalDateTime startTime, @Nullable LocalDateTime endTime, @Nullable String exitMessage,
+			List<String> arguments, @Nullable String errorMessage, @Nullable String externalExecutionId) {
 
 		this(executionId, exitCode, taskName, startTime, endTime, exitMessage, arguments, errorMessage,
 				externalExecutionId, null);
@@ -119,43 +122,43 @@ public long getExecutionId() {
 		return this.executionId;
 	}
 
-	public Integer getExitCode() {
+	public @Nullable Integer getExitCode() {
 		return this.exitCode;
 	}
 
-	public void setExitCode(Integer exitCode) {
+	public void setExitCode(@Nullable Integer exitCode) {
 		this.exitCode = exitCode;
 	}
 
-	public String getTaskName() {
+	public @Nullable String getTaskName() {
 		return this.taskName;
 	}
 
-	public void setTaskName(String taskName) {
+	public void setTaskName(@Nullable String taskName) {
 		this.taskName = taskName;
 	}
 
-	public LocalDateTime getStartTime() {
+	public @Nullable LocalDateTime getStartTime() {
 		return this.startTime;
 	}
 
-	public void setStartTime(LocalDateTime startTime) {
+	public void setStartTime(@Nullable LocalDateTime startTime) {
 		this.startTime = startTime;
 	}
 
-	public LocalDateTime getEndTime() {
+	public @Nullable LocalDateTime getEndTime() {
 		return this.endTime;
 	}
 
-	public void setEndTime(LocalDateTime endTime) {
+	public void setEndTime(@Nullable LocalDateTime endTime) {
 		this.endTime = endTime;
 	}
 
-	public String getExitMessage() {
+	public @Nullable String getExitMessage() {
 		return this.exitMessage;
 	}
 
-	public void setExitMessage(String exitMessage) {
+	public void setExitMessage(@Nullable String exitMessage) {
 		this.exitMessage = exitMessage;
 	}
 
@@ -167,27 +170,27 @@ public void setArguments(List<String> arguments) {
 		this.arguments = new ArrayList<>(arguments);
 	}
 
-	public String getErrorMessage() {
+	public @Nullable String getErrorMessage() {
 		return this.errorMessage;
 	}
 
-	public void setErrorMessage(String errorMessage) {
+	public void setErrorMessage(@Nullable String errorMessage) {
 		this.errorMessage = errorMessage;
 	}
 
-	public String getExternalExecutionId() {
+	public @Nullable String getExternalExecutionId() {
 		return this.externalExecutionId;
 	}
 
-	public void setExternalExecutionId(String externalExecutionId) {
+	public void setExternalExecutionId(@Nullable String externalExecutionId) {
 		this.externalExecutionId = externalExecutionId;
 	}
 
-	public Long getParentExecutionId() {
+	public @Nullable Long getParentExecutionId() {
 		return this.parentExecutionId;
 	}
 
-	public void setParentExecutionId(Long parentExecutionId) {
+	public void setParentExecutionId(@Nullable Long parentExecutionId) {
 		this.parentExecutionId = parentExecutionId;
 	}
 
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/TaskExplorer.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/TaskExplorer.java
index 13f05a178..8f5fd96f9 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/TaskExplorer.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/TaskExplorer.java
@@ -19,6 +19,8 @@
 import java.util.List;
 import java.util.Set;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
 
@@ -36,6 +38,7 @@ public interface TaskExplorer {
 	 * @param executionId the task execution id
 	 * @return the {@link TaskExecution} with this id, or null if not found
 	 */
+	@Nullable
 	TaskExecution getTaskExecution(long executionId);
 
 	/**
@@ -109,6 +112,7 @@ public interface TaskExplorer {
 	 * @param jobExecutionId the id of the JobExecution
 	 * @return the id of the {@link TaskExecution}
 	 */
+	@Nullable
 	Long getTaskExecutionIdByJobExecutionId(long jobExecutionId);
 
 	/**
@@ -147,6 +151,7 @@ public interface TaskExplorer {
 	 * @return The latest Task Execution or null
 	 * @see #getLatestTaskExecutionsByTaskNames(String...)
 	 */
+	@Nullable
 	TaskExecution getLatestTaskExecutionForTaskName(String taskName);
 
 }
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/TaskNameResolver.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/TaskNameResolver.java
index ae7a544ad..f2149a8fb 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/TaskNameResolver.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/TaskNameResolver.java
@@ -16,6 +16,8 @@
 
 package org.springframework.cloud.task.repository;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Strategy interface for customizing how the name of a task is determined.
  *
@@ -26,6 +28,7 @@ public interface TaskNameResolver {
 	/**
 	 * @return the name of the task being executed within this context.
 	 */
+	@Nullable
 	String getTaskName();
 
 }
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/TaskRepository.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/TaskRepository.java
index 3d2afa811..dceb8845c 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/TaskRepository.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/TaskRepository.java
@@ -19,6 +19,8 @@
 import java.time.LocalDateTime;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.transaction.annotation.Transactional;
 
 /**
@@ -40,7 +42,9 @@ public interface TaskRepository {
 	 * @return the updated {@link TaskExecution}
 	 */
 	@Transactional("${spring.cloud.task.transaction-manager:springCloudTaskTransactionManager}")
-	TaskExecution completeTaskExecution(long executionId, Integer exitCode, LocalDateTime endTime, String exitMessage);
+	@Nullable
+	TaskExecution completeTaskExecution(long executionId, Integer exitCode, LocalDateTime endTime,
+			@Nullable String exitMessage);
 
 	/**
 	 * Notifies the repository that a taskExecution has completed.
@@ -53,8 +57,9 @@ public interface TaskRepository {
 	 * @since 1.1.0
 	 */
 	@Transactional("${spring.cloud.task.transaction-manager:springCloudTaskTransactionManager}")
-	TaskExecution completeTaskExecution(long executionId, Integer exitCode, LocalDateTime endTime, String exitMessage,
-			String errorMessage);
+	@Nullable
+	TaskExecution completeTaskExecution(long executionId, Integer exitCode, LocalDateTime endTime,
+			@Nullable String exitMessage, @Nullable String errorMessage);
 
 	/**
 	 * Notifies the repository that a taskExecution needs to be created.
@@ -77,7 +82,7 @@ TaskExecution completeTaskExecution(long executionId, Integer exitCode, LocalDat
 	 * @return the initial {@link TaskExecution}
 	 */
 	@Transactional("${spring.cloud.task.transaction-manager:springCloudTaskTransactionManager}")
-	TaskExecution createTaskExecution(String name);
+	TaskExecution createTaskExecution(@Nullable String name);
 
 	/**
 	 * Creates an empty TaskExecution with just an id provided. This is intended to be
@@ -122,7 +127,7 @@ TaskExecution startTaskExecution(long executionid, String taskName, LocalDateTim
 	 * a TaskExecution.
 	 */
 	@Transactional("${spring.cloud.task.transaction-manager:springCloudTaskTransactionManager}")
-	TaskExecution startTaskExecution(long executionid, String taskName, LocalDateTime startTime, List<String> arguments,
-			String externalExecutionId, Long parentExecutionId);
+	TaskExecution startTaskExecution(long executionid, @Nullable String taskName, @Nullable LocalDateTime startTime,
+			List<String> arguments, @Nullable String externalExecutionId, @Nullable Long parentExecutionId);
 
 }
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/dao/JdbcTaskExecutionDao.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/dao/JdbcTaskExecutionDao.java
index 86bd11ac5..f3eda8c47 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/dao/JdbcTaskExecutionDao.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/dao/JdbcTaskExecutionDao.java
@@ -33,6 +33,8 @@
 
 import javax.sql.DataSource;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.batch.infrastructure.item.database.Order;
 import org.springframework.cloud.task.configuration.TaskProperties;
 import org.springframework.cloud.task.repository.TaskExecution;
@@ -181,6 +183,7 @@ public class JdbcTaskExecutionDao implements TaskExecutionDao {
 
 	private LinkedHashMap<String, Order> orderMap;
 
+	@SuppressWarnings("NullAway.Init")
 	private DataFieldMaxValueIncrementer taskIncrementer;
 
 	/**
@@ -209,14 +212,14 @@ public JdbcTaskExecutionDao(DataSource dataSource) {
 	}
 
 	@Override
-	public TaskExecution createTaskExecution(String taskName, LocalDateTime startTime, List<String> arguments,
-			String externalExecutionId) {
+	public TaskExecution createTaskExecution(@Nullable String taskName, @Nullable LocalDateTime startTime,
+			List<String> arguments, @Nullable String externalExecutionId) {
 		return createTaskExecution(taskName, startTime, arguments, externalExecutionId, null);
 	}
 
 	@Override
-	public TaskExecution createTaskExecution(String taskName, LocalDateTime startTime, List<String> arguments,
-			String externalExecutionId, Long parentExecutionId) {
+	public TaskExecution createTaskExecution(@Nullable String taskName, @Nullable LocalDateTime startTime,
+			List<String> arguments, @Nullable String externalExecutionId, @Nullable Long parentExecutionId) {
 		long nextExecutionId = getNextExecutionId();
 
 		TaskExecution taskExecution = new TaskExecution(nextExecutionId, null, taskName, startTime, null, null,
@@ -243,8 +246,9 @@ public TaskExecution startTaskExecution(long executionId, String taskName, Local
 	}
 
 	@Override
-	public TaskExecution startTaskExecution(long executionId, String taskName, LocalDateTime startTime,
-			List<String> arguments, String externalExecutionId, Long parentExecutionId) {
+	public TaskExecution startTaskExecution(long executionId, @Nullable String taskName,
+			@Nullable LocalDateTime startTime, List<String> arguments, @Nullable String externalExecutionId,
+			@Nullable Long parentExecutionId) {
 		TaskExecution taskExecution = new TaskExecution(executionId, null, taskName, startTime, null, null, arguments,
 				null, externalExecutionId, parentExecutionId);
 
@@ -272,15 +276,16 @@ public TaskExecution startTaskExecution(long executionId, String taskName, Local
 	}
 
 	@Override
-	public void completeTaskExecution(long taskExecutionId, Integer exitCode, LocalDateTime endTime, String exitMessage,
-			String errorMessage) {
+	public void completeTaskExecution(long taskExecutionId, Integer exitCode, LocalDateTime endTime,
+			@Nullable String exitMessage, @Nullable String errorMessage) {
 		final MapSqlParameterSource queryParameters = new MapSqlParameterSource().addValue("taskExecutionId",
 				taskExecutionId, Types.BIGINT);
 
 		// Check if given TaskExecution's Id already exists, if none is found
 		// it is invalid and an exception should be thrown.
-		if (this.jdbcTemplate.queryForObject(getQuery(CHECK_TASK_EXECUTION_EXISTS), queryParameters,
-				Integer.class) != 1) {
+		Integer count = this.jdbcTemplate.queryForObject(getQuery(CHECK_TASK_EXECUTION_EXISTS), queryParameters,
+				Integer.class);
+		if (count == null || count != 1) {
 			throw new IllegalStateException("Invalid TaskExecution, ID " + taskExecutionId + " not found.");
 		}
 
@@ -297,18 +302,19 @@ public void completeTaskExecution(long taskExecutionId, Integer exitCode, LocalD
 
 	@Override
 	public void completeTaskExecution(long taskExecutionId, Integer exitCode, LocalDateTime endTime,
-			String exitMessage) {
+			@Nullable String exitMessage) {
 		completeTaskExecution(taskExecutionId, exitCode, endTime, exitMessage, null);
 	}
 
 	@Override
-	public TaskExecution getTaskExecution(long executionId) {
+	public @Nullable TaskExecution getTaskExecution(long executionId) {
 		final MapSqlParameterSource queryParameters = new MapSqlParameterSource().addValue("taskExecutionId",
 				executionId, Types.BIGINT);
 
 		try {
 			TaskExecution taskExecution = this.jdbcTemplate.queryForObject(getQuery(GET_EXECUTION_BY_ID),
 					queryParameters, new TaskExecutionRowMapper());
+			Assert.state(taskExecution != null, "TaskExecution must not be null");
 			taskExecution.setArguments(getTaskArguments(executionId));
 			return taskExecution;
 		}
@@ -324,8 +330,9 @@ public long getTaskExecutionCountByTaskName(String taskName) {
 				Types.VARCHAR);
 
 		try {
-			return this.jdbcTemplate.queryForObject(getQuery(TASK_EXECUTION_COUNT_BY_NAME), queryParameters,
+			Long count = this.jdbcTemplate.queryForObject(getQuery(TASK_EXECUTION_COUNT_BY_NAME), queryParameters,
 					Long.class);
+			return count != null ? count : 0;
 		}
 		catch (EmptyResultDataAccessException e) {
 			return 0;
@@ -338,8 +345,9 @@ public long getRunningTaskExecutionCountByTaskName(String taskName) {
 				Types.VARCHAR);
 
 		try {
-			return this.jdbcTemplate.queryForObject(getQuery(RUNNING_TASK_EXECUTION_COUNT_BY_NAME), queryParameters,
-					Long.class);
+			Long count = this.jdbcTemplate.queryForObject(getQuery(RUNNING_TASK_EXECUTION_COUNT_BY_NAME),
+					queryParameters, Long.class);
+			return count != null ? count : 0;
 		}
 		catch (EmptyResultDataAccessException e) {
 			return 0;
@@ -351,8 +359,9 @@ public long getRunningTaskExecutionCount() {
 
 		try {
 			final MapSqlParameterSource queryParameters = new MapSqlParameterSource();
-			return this.jdbcTemplate.queryForObject(getQuery(RUNNING_TASK_EXECUTION_COUNT), queryParameters,
+			Long count = this.jdbcTemplate.queryForObject(getQuery(RUNNING_TASK_EXECUTION_COUNT), queryParameters,
 					Long.class);
+			return count != null ? count : 0;
 		}
 		catch (EmptyResultDataAccessException e) {
 			return 0;
@@ -386,7 +395,7 @@ public List<TaskExecution> getLatestTaskExecutionsByTaskNames(String... taskName
 	}
 
 	@Override
-	public TaskExecution getLatestTaskExecutionForTaskName(String taskName) {
+	public @Nullable TaskExecution getLatestTaskExecutionForTaskName(String taskName) {
 		Assert.hasText(taskName, "The task name must not be empty.");
 		final List<TaskExecution> taskExecutions = this.getLatestTaskExecutionsByTaskNames(taskName);
 		if (taskExecutions.isEmpty()) {
@@ -405,8 +414,9 @@ else if (taskExecutions.size() == 1) {
 	public long getTaskExecutionCount() {
 
 		try {
-			return this.jdbcTemplate.queryForObject(getQuery(TASK_EXECUTION_COUNT), new MapSqlParameterSource(),
+			Long count = this.jdbcTemplate.queryForObject(getQuery(TASK_EXECUTION_COUNT), new MapSqlParameterSource(),
 					Long.class);
+			return count != null ? count : 0;
 		}
 		catch (EmptyResultDataAccessException e) {
 			return 0;
@@ -432,8 +442,9 @@ public long getTaskExecutionCountByExternalExecutionId(String externalExecutionI
 				externalExecutionId, Types.VARCHAR);
 
 		try {
-			return this.jdbcTemplate.queryForObject(getQuery(TASK_EXECUTION_COUNT_BY_EXTERNAL_EXECUTION_ID),
+			Long count = this.jdbcTemplate.queryForObject(getQuery(TASK_EXECUTION_COUNT_BY_EXTERNAL_EXECUTION_ID),
 					queryParameters, Long.class);
+			return count != null ? count : 0;
 		}
 		catch (EmptyResultDataAccessException e) {
 			return 0;
@@ -447,6 +458,7 @@ public Page<TaskExecution> findTaskExecutionsByName(String taskName, Pageable pa
 	}
 
 	@Override
+	@SuppressWarnings("NullAway")
 	public List<String> getTaskNames() {
 		return this.jdbcTemplate.queryForList(getQuery(FIND_TASK_NAMES), new MapSqlParameterSource(), String.class);
 	}
@@ -466,13 +478,14 @@ public long getNextExecutionId() {
 	}
 
 	@Override
-	public Long getTaskExecutionIdByJobExecutionId(long jobExecutionId) {
+	public @Nullable Long getTaskExecutionIdByJobExecutionId(long jobExecutionId) {
 		final MapSqlParameterSource queryParameters = new MapSqlParameterSource().addValue("jobExecutionId",
 				jobExecutionId, Types.BIGINT);
 
 		try {
-			return this.jdbcTemplate.queryForObject(getQuery(FIND_TASK_EXECUTION_BY_JOB_EXECUTION_ID), queryParameters,
-					Long.class);
+			Long taskExecutionId = this.jdbcTemplate.queryForObject(getQuery(FIND_TASK_EXECUTION_BY_JOB_EXECUTION_ID),
+					queryParameters, Long.class);
+			return taskExecutionId;
 		}
 		catch (EmptyResultDataAccessException e) {
 			return null;
@@ -485,8 +498,8 @@ public Set<Long> getJobExecutionIdsByTaskExecutionId(long taskExecutionId) {
 				taskExecutionId, Types.BIGINT);
 
 		try {
-			return this.jdbcTemplate.query(getQuery(FIND_JOB_EXECUTION_BY_TASK_EXECUTION_ID), queryParameters,
-					new ResultSetExtractor<Set<Long>>() {
+			Set<Long> result = this.jdbcTemplate.query(getQuery(FIND_JOB_EXECUTION_BY_TASK_EXECUTION_ID),
+					queryParameters, new ResultSetExtractor<Set<Long>>() {
 						@Override
 						public Set<Long> extractData(ResultSet resultSet) throws SQLException, DataAccessException {
 							Set<Long> jobExecutionIds = new TreeSet<>();
@@ -498,6 +511,7 @@ public Set<Long> extractData(ResultSet resultSet) throws SQLException, DataAcces
 							return jobExecutionIds;
 						}
 					});
+			return result != null ? result : Collections.emptySet();
 		}
 		catch (DataAccessException e) {
 			return Collections.emptySet();
@@ -516,7 +530,7 @@ public void updateExternalExecutionId(long taskExecutionId, String externalExecu
 	}
 
 	private Page<TaskExecution> queryForPageableResults(Pageable pageable, String selectClause, String fromClause,
-			String whereClause, MapSqlParameterSource queryParameters, long totalCount) {
+			@Nullable String whereClause, MapSqlParameterSource queryParameters, long totalCount) {
 		SqlPagingQueryProviderFactoryBean factoryBean = new SqlPagingQueryProviderFactoryBean();
 		factoryBean.setSelectClause(selectClause);
 		factoryBean.setFromClause(fromClause);
@@ -624,7 +638,8 @@ public TaskExecution mapRow(ResultSet rs, int rowNum) throws SQLException {
 				startTime = rs.getObject("START_TIME", LocalDateTime.class);
 			}
 			catch (NullPointerException npe) {
-				if (!npe.getMessage().contains("<local4>")) {
+				String message = npe.getMessage();
+				if (message == null || !message.contains("<local4>")) {
 					throw npe;
 				}
 			}
@@ -633,7 +648,8 @@ public TaskExecution mapRow(ResultSet rs, int rowNum) throws SQLException {
 				endTime = rs.getObject("END_TIME", LocalDateTime.class);
 			}
 			catch (NullPointerException npe) {
-				if (!npe.getMessage().contains("<local4>")) {
+				String message = npe.getMessage();
+				if (message == null || !message.contains("<local4>")) {
 					throw npe;
 				}
 			}
@@ -642,7 +658,7 @@ public TaskExecution mapRow(ResultSet rs, int rowNum) throws SQLException {
 					rs.getString("EXTERNAL_EXECUTION_ID"), parentExecutionId);
 		}
 
-		private Integer getNullableExitCode(ResultSet rs) throws SQLException {
+		private @Nullable Integer getNullableExitCode(ResultSet rs) throws SQLException {
 			int exitCode = rs.getInt("EXIT_CODE");
 			return !rs.wasNull() ? exitCode : null;
 		}
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/dao/MapTaskExecutionDao.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/dao/MapTaskExecutionDao.java
index b6087caac..6dde6630b 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/dao/MapTaskExecutionDao.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/dao/MapTaskExecutionDao.java
@@ -30,6 +30,8 @@
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.atomic.AtomicLong;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.cloud.task.repository.TaskExecution;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.PageImpl;
@@ -58,14 +60,14 @@ public MapTaskExecutionDao() {
 	}
 
 	@Override
-	public TaskExecution createTaskExecution(String taskName, LocalDateTime startTime, List<String> arguments,
-			String externalExecutionId) {
+	public TaskExecution createTaskExecution(@Nullable String taskName, @Nullable LocalDateTime startTime,
+			List<String> arguments, @Nullable String externalExecutionId) {
 		return createTaskExecution(taskName, startTime, arguments, externalExecutionId, null);
 	}
 
 	@Override
-	public TaskExecution createTaskExecution(String taskName, LocalDateTime startTime, List<String> arguments,
-			String externalExecutionId, Long parentExecutionId) {
+	public TaskExecution createTaskExecution(@Nullable String taskName, @Nullable LocalDateTime startTime,
+			List<String> arguments, @Nullable String externalExecutionId, @Nullable Long parentExecutionId) {
 		long taskExecutionId = getNextExecutionId();
 		TaskExecution taskExecution = new TaskExecution(taskExecutionId, null, taskName, startTime, null, null,
 				arguments, null, externalExecutionId, parentExecutionId);
@@ -80,9 +82,11 @@ public TaskExecution startTaskExecution(long executionId, String taskName, Local
 	}
 
 	@Override
-	public TaskExecution startTaskExecution(long executionId, String taskName, LocalDateTime startTime,
-			List<String> arguments, String externalExecutionid, Long parentExecutionId) {
+	public TaskExecution startTaskExecution(long executionId, @Nullable String taskName,
+			@Nullable LocalDateTime startTime, List<String> arguments, @Nullable String externalExecutionid,
+			@Nullable Long parentExecutionId) {
 		TaskExecution taskExecution = this.taskExecutions.get(executionId);
+		Assert.state(taskExecution != null, "TaskExecution with ID " + executionId + " not found.");
 		taskExecution.setTaskName(taskName);
 		taskExecution.setStartTime(startTime);
 		taskExecution.setArguments(arguments);
@@ -94,8 +98,8 @@ public TaskExecution startTaskExecution(long executionId, String taskName, Local
 	}
 
 	@Override
-	public void completeTaskExecution(long executionId, Integer exitCode, LocalDateTime endTime, String exitMessage,
-			String errorMessage) {
+	public void completeTaskExecution(long executionId, Integer exitCode, LocalDateTime endTime,
+			@Nullable String exitMessage, @Nullable String errorMessage) {
 		if (!this.taskExecutions.containsKey(executionId)) {
 			throw new IllegalStateException("Invalid TaskExecution, ID " + executionId + " not found.");
 		}
@@ -108,12 +112,13 @@ public void completeTaskExecution(long executionId, Integer exitCode, LocalDateT
 	}
 
 	@Override
-	public void completeTaskExecution(long executionId, Integer exitCode, LocalDateTime endTime, String exitMessage) {
+	public void completeTaskExecution(long executionId, Integer exitCode, LocalDateTime endTime,
+			@Nullable String exitMessage) {
 		completeTaskExecution(executionId, exitCode, endTime, exitMessage, null);
 	}
 
 	@Override
-	public TaskExecution getTaskExecution(long executionId) {
+	public @Nullable TaskExecution getTaskExecution(long executionId) {
 		return this.taskExecutions.get(executionId);
 	}
 
@@ -121,7 +126,8 @@ public TaskExecution getTaskExecution(long executionId) {
 	public long getTaskExecutionCountByTaskName(String taskName) {
 		int count = 0;
 		for (Map.Entry<Long, TaskExecution> entry : this.taskExecutions.entrySet()) {
-			if (entry.getValue().getTaskName().equals(taskName)) {
+			String entryTaskName = entry.getValue().getTaskName();
+			if (entryTaskName != null && entryTaskName.equals(taskName)) {
 				count++;
 			}
 		}
@@ -132,7 +138,8 @@ public long getTaskExecutionCountByTaskName(String taskName) {
 	public long getTaskExecutionCountByExternalExecutionId(String externalExecutionId) {
 		int count = 0;
 		for (Map.Entry<Long, TaskExecution> entry : this.taskExecutions.entrySet()) {
-			if (entry.getValue().getExternalExecutionId().equals(externalExecutionId)) {
+			String entryExternalId = entry.getValue().getExternalExecutionId();
+			if (entryExternalId != null && entryExternalId.equals(externalExecutionId)) {
 				count++;
 			}
 		}
@@ -143,7 +150,8 @@ public long getTaskExecutionCountByExternalExecutionId(String externalExecutionI
 	public long getRunningTaskExecutionCountByTaskName(String taskName) {
 		int count = 0;
 		for (Map.Entry<Long, TaskExecution> entry : this.taskExecutions.entrySet()) {
-			if (entry.getValue().getTaskName().equals(taskName) && entry.getValue().getEndTime() == null) {
+			String entryTaskName = entry.getValue().getTaskName();
+			if (entryTaskName != null && entryTaskName.equals(taskName) && entry.getValue().getEndTime() == null) {
 				count++;
 			}
 		}
@@ -170,7 +178,8 @@ public long getTaskExecutionCount() {
 	public Page<TaskExecution> findRunningTaskExecutions(String taskName, Pageable pageable) {
 		Set<TaskExecution> result = getTaskExecutionTreeSet();
 		for (Map.Entry<Long, TaskExecution> entry : this.taskExecutions.entrySet()) {
-			if (entry.getValue().getTaskName().equals(taskName) && entry.getValue().getEndTime() == null) {
+			String entryTaskName = entry.getValue().getTaskName();
+			if (entryTaskName != null && entryTaskName.equals(taskName) && entry.getValue().getEndTime() == null) {
 				result.add(entry.getValue());
 			}
 		}
@@ -181,7 +190,8 @@ public Page<TaskExecution> findRunningTaskExecutions(String taskName, Pageable p
 	public Page<TaskExecution> findTaskExecutionsByExternalExecutionId(String externalExecutionId, Pageable pageable) {
 		Set<TaskExecution> result = getTaskExecutionTreeSet();
 		for (Map.Entry<Long, TaskExecution> entry : this.taskExecutions.entrySet()) {
-			if (entry.getValue().getExternalExecutionId().equals(externalExecutionId)) {
+			String entryExternalId = entry.getValue().getExternalExecutionId();
+			if (entryExternalId != null && entryExternalId.equals(externalExecutionId)) {
 				result.add(entry.getValue());
 			}
 		}
@@ -193,7 +203,8 @@ public Page<TaskExecution> findTaskExecutionsByExternalExecutionId(String extern
 	public Page<TaskExecution> findTaskExecutionsByName(String taskName, Pageable pageable) {
 		Set<TaskExecution> filteredSet = getTaskExecutionTreeSet();
 		for (Map.Entry<Long, TaskExecution> entry : this.taskExecutions.entrySet()) {
-			if (entry.getValue().getTaskName().equals(taskName)) {
+			String entryTaskName = entry.getValue().getTaskName();
+			if (entryTaskName != null && entryTaskName.equals(taskName)) {
 				filteredSet.add(entry.getValue());
 			}
 		}
@@ -226,7 +237,7 @@ public long getNextExecutionId() {
 	}
 
 	@Override
-	public Long getTaskExecutionIdByJobExecutionId(long jobExecutionId) {
+	public @Nullable Long getTaskExecutionIdByJobExecutionId(long jobExecutionId) {
 		Long taskId = null;
 
 		found:
@@ -268,7 +279,11 @@ private TreeSet<TaskExecution> getTaskExecutionTreeSet() {
 		return new TreeSet<>(new Comparator<TaskExecution>() {
 			@Override
 			public int compare(TaskExecution e1, TaskExecution e2) {
-				int result = e1.getStartTime().compareTo(e2.getStartTime());
+				LocalDateTime startTime1 = e1.getStartTime();
+				LocalDateTime startTime2 = e2.getStartTime();
+				Assert.state(startTime1 != null, "TaskExecution start time must not be null");
+				Assert.state(startTime2 != null, "TaskExecution start time must not be null");
+				int result = startTime1.compareTo(startTime2);
 				if (result == 0) {
 					result = Long.valueOf(e1.getExecutionId()).compareTo(e2.getExecutionId());
 				}
@@ -284,6 +299,7 @@ private Page getPageFromList(List<TaskExecution> executionList, Pageable pageabl
 	}
 
 	@Override
+	@SuppressWarnings("NullAway")
 	public List<TaskExecution> getLatestTaskExecutionsByTaskNames(String... taskNames) {
 
 		Assert.notEmpty(taskNames, "At least 1 task name must be provided.");
@@ -324,7 +340,7 @@ public List<TaskExecution> getLatestTaskExecutionsByTaskNames(String... taskName
 	}
 
 	@Override
-	public TaskExecution getLatestTaskExecutionForTaskName(String taskName) {
+	public @Nullable TaskExecution getLatestTaskExecutionForTaskName(String taskName) {
 		Assert.hasText(taskName, "The task name must not be empty.");
 		final List<TaskExecution> taskExecutions = this.getLatestTaskExecutionsByTaskNames(taskName);
 		if (taskExecutions.isEmpty()) {
@@ -343,11 +359,15 @@ private static final class TaskExecutionComparator implements Comparator<TaskExe
 
 		@Override
 		public int compare(TaskExecution firstTaskExecution, TaskExecution secondTaskExecution) {
-			if (firstTaskExecution.getStartTime().equals(secondTaskExecution.getStartTime())) {
+			LocalDateTime firstStartTime = firstTaskExecution.getStartTime();
+			LocalDateTime secondStartTime = secondTaskExecution.getStartTime();
+			Assert.state(firstStartTime != null, "TaskExecution start time must not be null");
+			Assert.state(secondStartTime != null, "TaskExecution start time must not be null");
+			if (firstStartTime.equals(secondStartTime)) {
 				return Long.compare(firstTaskExecution.getExecutionId(), secondTaskExecution.getExecutionId());
 			}
 			else {
-				return secondTaskExecution.getStartTime().compareTo(firstTaskExecution.getStartTime());
+				return secondStartTime.compareTo(firstStartTime);
 			}
 		}
 
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/dao/TaskExecutionDao.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/dao/TaskExecutionDao.java
index 645a6cdd5..d373f1de6 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/dao/TaskExecutionDao.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/dao/TaskExecutionDao.java
@@ -20,6 +20,8 @@
 import java.util.List;
 import java.util.Set;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.cloud.task.repository.TaskExecution;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Pageable;
@@ -42,8 +44,8 @@ public interface TaskExecutionDao {
 	 * @param externalExecutionId id assigned to the task by the platform
 	 * @return A fully qualified {@link TaskExecution} instance.
 	 */
-	TaskExecution createTaskExecution(String taskName, LocalDateTime startTime, List<String> arguments,
-			String externalExecutionId);
+	TaskExecution createTaskExecution(@Nullable String taskName, @Nullable LocalDateTime startTime,
+			List<String> arguments, @Nullable String externalExecutionId);
 
 	/**
 	 * Save a new {@link TaskExecution}.
@@ -55,8 +57,8 @@ TaskExecution createTaskExecution(String taskName, LocalDateTime startTime, List
 	 * @return A fully qualified {@link TaskExecution} instance.
 	 * @since 1.2.0
 	 */
-	TaskExecution createTaskExecution(String taskName, LocalDateTime startTime, List<String> arguments,
-			String externalExecutionId, Long parentExecutionId);
+	TaskExecution createTaskExecution(@Nullable String taskName, @Nullable LocalDateTime startTime,
+			List<String> arguments, @Nullable String externalExecutionId, @Nullable Long parentExecutionId);
 
 	/**
 	 * Update and existing {@link TaskExecution} to mark it as started.
@@ -84,8 +86,8 @@ TaskExecution startTaskExecution(long executionId, String taskName, LocalDateTim
 	 * start.
 	 * @since 1.2.0
 	 */
-	TaskExecution startTaskExecution(long executionId, String taskName, LocalDateTime startTime, List<String> arguments,
-			String externalExecutionId, Long parentExecutionId);
+	TaskExecution startTaskExecution(long executionId, @Nullable String taskName, @Nullable LocalDateTime startTime,
+			List<String> arguments, @Nullable String externalExecutionId, @Nullable Long parentExecutionId);
 
 	/**
 	 * Update and existing {@link TaskExecution} to mark it as completed.
@@ -96,8 +98,8 @@ TaskExecution startTaskExecution(long executionId, String taskName, LocalDateTim
 	 * @param errorMessage error information available upon failure of a task.
 	 * @since 1.1.0
 	 */
-	void completeTaskExecution(long executionId, Integer exitCode, LocalDateTime endTime, String exitMessage,
-			String errorMessage);
+	void completeTaskExecution(long executionId, Integer exitCode, LocalDateTime endTime, @Nullable String exitMessage,
+			@Nullable String errorMessage);
 
 	/**
 	 * Update and existing {@link TaskExecution}.
@@ -106,13 +108,14 @@ void completeTaskExecution(long executionId, Integer exitCode, LocalDateTime end
 	 * @param endTime the time the task completed.
 	 * @param exitMessage the message assigned to the task upon completion.
 	 */
-	void completeTaskExecution(long executionId, Integer exitCode, LocalDateTime endTime, String exitMessage);
+	void completeTaskExecution(long executionId, Integer exitCode, LocalDateTime endTime, @Nullable String exitMessage);
 
 	/**
 	 * Retrieves a task execution from the task repository.
 	 * @param executionId the id associated with the task execution.
 	 * @return a fully qualified TaskExecution instance.
 	 */
+	@Nullable
 	TaskExecution getTaskExecution(long executionId);
 
 	/**
@@ -203,6 +206,7 @@ void completeTaskExecution(long executionId, Integer exitCode, LocalDateTime end
 	 * @param jobExecutionId the id of the JobExecution
 	 * @return the id of the {@link TaskExecution}
 	 */
+	@Nullable
 	Long getTaskExecutionIdByJobExecutionId(long jobExecutionId);
 
 	/**
@@ -247,6 +251,7 @@ void completeTaskExecution(long executionId, Integer exitCode, LocalDateTime end
 	 * @return The latest Task Execution or null
 	 * @see #getLatestTaskExecutionsByTaskNames(String...)
 	 */
+	@Nullable
 	TaskExecution getLatestTaskExecutionForTaskName(String taskName);
 
 }
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/dao/package-info.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/dao/package-info.java
index cdc9ec673..8d05957cd 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/dao/package-info.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/dao/package-info.java
@@ -18,4 +18,7 @@
  * Interface DAO and default implementations for storing and retrieving data for tasks
  * from a repository.
  */
+@NullMarked
 package org.springframework.cloud.task.repository.dao;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/database/package-info.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/database/package-info.java
index 7833e66b0..69490599e 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/database/package-info.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/database/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Database-specific components for Spring Cloud Task repository.
  */
+@NullMarked
 package org.springframework.cloud.task.repository.database;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/database/support/AbstractSqlPagingQueryProvider.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/database/support/AbstractSqlPagingQueryProvider.java
index edef0ab4c..96dc0594f 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/database/support/AbstractSqlPagingQueryProvider.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/database/support/AbstractSqlPagingQueryProvider.java
@@ -24,6 +24,8 @@
 
 import javax.sql.DataSource;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.batch.infrastructure.item.database.JdbcParameterUtils;
 import org.springframework.batch.infrastructure.item.database.Order;
 import org.springframework.cloud.task.repository.database.PagingQueryProvider;
@@ -46,11 +48,13 @@
  */
 public abstract class AbstractSqlPagingQueryProvider implements PagingQueryProvider {
 
+	@SuppressWarnings("NullAway.Init")
 	private String selectClause;
 
+	@SuppressWarnings("NullAway.Init")
 	private String fromClause;
 
-	private String whereClause;
+	private @Nullable String whereClause;
 
 	private Map<String, Order> sortKeys = new LinkedHashMap<>();
 
@@ -89,14 +93,14 @@ public void setFromClause(String fromClause) {
 	/**
 	 * @return SQL WHERE clause part of SQL query string
 	 */
-	protected String getWhereClause() {
+	protected @Nullable String getWhereClause() {
 		return this.whereClause;
 	}
 
 	/**
 	 * @param whereClause WHERE clause part of SQL query string
 	 */
-	public void setWhereClause(String whereClause) {
+	public void setWhereClause(@Nullable String whereClause) {
 		if (StringUtils.hasText(whereClause)) {
 			this.whereClause = removeKeyWord("where", whereClause);
 		}
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/database/support/SqlPagingQueryProviderFactoryBean.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/database/support/SqlPagingQueryProviderFactoryBean.java
index 9e373268f..850eca465 100755
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/database/support/SqlPagingQueryProviderFactoryBean.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/database/support/SqlPagingQueryProviderFactoryBean.java
@@ -22,6 +22,8 @@
 
 import javax.sql.DataSource;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.batch.infrastructure.item.database.Order;
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.cloud.task.repository.database.PagingQueryProvider;
@@ -51,16 +53,20 @@
  */
 public class SqlPagingQueryProviderFactoryBean implements FactoryBean<PagingQueryProvider> {
 
+	@SuppressWarnings("NullAway.Init")
 	private DataSource dataSource;
 
-	private String databaseType;
+	private @Nullable String databaseType;
 
+	@SuppressWarnings("NullAway.Init")
 	private String fromClause;
 
-	private String whereClause;
+	private @Nullable String whereClause;
 
+	@SuppressWarnings("NullAway.Init")
 	private String selectClause;
 
+	@SuppressWarnings("NullAway.Init")
 	private Map<String, Order> sortKeys;
 
 	private Map<DatabaseType, AbstractSqlPagingQueryProvider> providers = new HashMap<>();
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/database/support/package-info.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/database/support/package-info.java
index 524b0076c..5cdfec580 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/database/support/package-info.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/database/support/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Support classes for database-specific Spring Cloud Task repository implementations.
  */
+@NullMarked
 package org.springframework.cloud.task.repository.database.support;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/package-info.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/package-info.java
index f5dd6a9ff..779fd5146 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/package-info.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Core repository interfaces and classes for Spring Cloud Task.
  */
+@NullMarked
 package org.springframework.cloud.task.repository;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/DatabaseType.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/DatabaseType.java
index 009665290..b224b415b 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/DatabaseType.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/DatabaseType.java
@@ -23,6 +23,8 @@
 
 import javax.sql.DataSource;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.jdbc.support.DatabaseMetaDataCallback;
 import org.springframework.jdbc.support.JdbcUtils;
 import org.springframework.jdbc.support.MetaDataAccessException;
@@ -114,7 +116,8 @@ public enum DatabaseType {
 	 * @return DatabaseType The database type associated with the datasource.
 	 * @throws MetaDataAccessException thrown if failure occurs on metadata lookup.
 	 */
-	public static DatabaseType fromMetaData(DataSource dataSource) throws SQLException, MetaDataAccessException {
+	public static @Nullable DatabaseType fromMetaData(DataSource dataSource)
+			throws SQLException, MetaDataAccessException {
 		String databaseProductName = JdbcUtils.extractDatabaseMetaData(dataSource, new DatabaseMetaDataCallback() {
 
 			@Override
@@ -163,7 +166,7 @@ else if (databaseProductName.indexOf("AS") != -1 && (databaseProductVersion.star
 	 * @return DatabaseType for given product name.
 	 * @throws IllegalArgumentException if none is found.
 	 */
-	public static DatabaseType fromProductName(String productName) {
+	public static DatabaseType fromProductName(@Nullable String productName) {
 		if (!dbNameMap.containsKey(productName)) {
 			throw new IllegalArgumentException("DatabaseType not found for product name: [" + productName + "]");
 		}
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/SimpleTaskExplorer.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/SimpleTaskExplorer.java
index 4cc5d8a7f..2c0222fb1 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/SimpleTaskExplorer.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/SimpleTaskExplorer.java
@@ -19,6 +19,8 @@
 import java.util.List;
 import java.util.Set;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.cloud.task.repository.TaskExecution;
 import org.springframework.cloud.task.repository.TaskExplorer;
 import org.springframework.cloud.task.repository.dao.TaskExecutionDao;
@@ -50,7 +52,7 @@ public SimpleTaskExplorer(TaskExecutionDaoFactoryBean taskExecutionDaoFactoryBea
 	}
 
 	@Override
-	public TaskExecution getTaskExecution(long executionId) {
+	public @Nullable TaskExecution getTaskExecution(long executionId) {
 		return this.taskExecutionDao.getTaskExecution(executionId);
 	}
 
@@ -100,7 +102,7 @@ public Page<TaskExecution> findAll(Pageable pageable) {
 	}
 
 	@Override
-	public Long getTaskExecutionIdByJobExecutionId(long jobExecutionId) {
+	public @Nullable Long getTaskExecutionIdByJobExecutionId(long jobExecutionId) {
 		return this.taskExecutionDao.getTaskExecutionIdByJobExecutionId(jobExecutionId);
 	}
 
@@ -115,7 +117,7 @@ public List<TaskExecution> getLatestTaskExecutionsByTaskNames(String... taskName
 	}
 
 	@Override
-	public TaskExecution getLatestTaskExecutionForTaskName(String taskName) {
+	public @Nullable TaskExecution getLatestTaskExecutionForTaskName(String taskName) {
 		return this.taskExecutionDao.getLatestTaskExecutionForTaskName(taskName);
 	}
 
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/SimpleTaskNameResolver.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/SimpleTaskNameResolver.java
index 7709f5d49..1364623ff 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/SimpleTaskNameResolver.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/SimpleTaskNameResolver.java
@@ -16,6 +16,8 @@
 
 package org.springframework.cloud.task.repository.support;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.annotation.Value;
 import org.springframework.cloud.task.repository.TaskNameResolver;
@@ -36,8 +38,10 @@
  */
 public class SimpleTaskNameResolver implements TaskNameResolver, ApplicationContextAware {
 
+	@SuppressWarnings("NullAway.Init")
 	private ApplicationContext context;
 
+	@SuppressWarnings("NullAway.Init")
 	private String configuredName;
 
 	@Value("${spring.cloud.task.name:}")
@@ -51,12 +55,12 @@ public void setApplicationContext(ApplicationContext applicationContext) throws
 	}
 
 	@Override
-	public String getTaskName() {
+	public @Nullable String getTaskName() {
 		if (StringUtils.hasText(this.configuredName)) {
 			return this.configuredName;
 		}
 		else {
-			return this.context.getId().replace(":", "_");
+			return (this.context.getId() != null) ? this.context.getId().replace(":", "_") : null;
 		}
 	}
 
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/SimpleTaskRepository.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/SimpleTaskRepository.java
index 3ae4febf4..04420744e 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/SimpleTaskRepository.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/SimpleTaskRepository.java
@@ -19,9 +19,11 @@
 import java.time.LocalDateTime;
 import java.util.Collections;
 import java.util.List;
+import java.util.Objects;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.beans.factory.FactoryBean;
 import org.springframework.cloud.task.repository.TaskExecution;
@@ -53,6 +55,7 @@ public class SimpleTaskRepository implements TaskRepository {
 
 	private static final Log logger = LogFactory.getLog(SimpleTaskRepository.class);
 
+	@SuppressWarnings("NullAway.Init")
 	private TaskExecutionDao taskExecutionDao;
 
 	private FactoryBean<TaskExecutionDao> taskExecutionDaoFactoryBean;
@@ -87,19 +90,21 @@ public SimpleTaskRepository(FactoryBean<TaskExecutionDao> taskExecutionDaoFactor
 	}
 
 	@Override
-	public TaskExecution completeTaskExecution(long executionId, Integer exitCode, LocalDateTime endTime,
-			String exitMessage) {
+	public @Nullable TaskExecution completeTaskExecution(long executionId, Integer exitCode, LocalDateTime endTime,
+			@Nullable String exitMessage) {
 		return completeTaskExecution(executionId, exitCode, endTime, exitMessage, null);
 	}
 
 	@Override
-	public TaskExecution completeTaskExecution(long executionId, Integer exitCode, LocalDateTime endTime,
-			String exitMessage, String errorMessage) {
+	public @Nullable TaskExecution completeTaskExecution(long executionId, Integer exitCode, LocalDateTime endTime,
+			@Nullable String exitMessage, @Nullable String errorMessage) {
 		initialize();
 
 		validateCompletedTaskExitInformation(executionId, exitCode, endTime);
 		exitMessage = trimMessage(exitMessage, this.maxExitMessageSize);
-		errorMessage = trimMessage(errorMessage, this.maxErrorMessageSize);
+		if (errorMessage != null) {
+			errorMessage = trimMessage(errorMessage, this.maxErrorMessageSize);
+		}
 		this.taskExecutionDao.completeTaskExecution(executionId, exitCode, endTime, exitMessage, errorMessage);
 		logger.debug("Updating: TaskExecution with executionId=" + executionId + " with the following {" + "exitCode="
 				+ exitCode + ", endTime=" + endTime + ", exitMessage='" + exitMessage + '\'' + ", errorMessage='"
@@ -120,7 +125,7 @@ public TaskExecution createTaskExecution(TaskExecution taskExecution) {
 	}
 
 	@Override
-	public TaskExecution createTaskExecution(String name) {
+	public TaskExecution createTaskExecution(@Nullable String name) {
 		initialize();
 		TaskExecution taskExecution = this.taskExecutionDao.createTaskExecution(name, null,
 				Collections.<String>emptyList(), null);
@@ -146,8 +151,9 @@ public void updateExternalExecutionId(long executionid, String externalExecution
 	}
 
 	@Override
-	public TaskExecution startTaskExecution(long executionid, String taskName, LocalDateTime startTime,
-			List<String> arguments, String externalExecutionId, Long parentExecutionId) {
+	public TaskExecution startTaskExecution(long executionid, @Nullable String taskName,
+			@Nullable LocalDateTime startTime, List<String> arguments, @Nullable String externalExecutionId,
+			@Nullable Long parentExecutionId) {
 		initialize();
 		TaskExecution taskExecution = this.taskExecutionDao.startTaskExecution(executionid, taskName, startTime,
 				arguments, externalExecutionId, parentExecutionId);
@@ -167,7 +173,8 @@ public TaskExecutionDao getTaskExecutionDao() {
 	private void initialize() {
 		if (!this.initialized) {
 			try {
-				this.taskExecutionDao = this.taskExecutionDaoFactoryBean.getObject();
+				this.taskExecutionDao = Objects.requireNonNull(this.taskExecutionDaoFactoryBean.getObject(),
+						"taskexecutionDaoFactoryBean object is required");
 				this.initialized = true;
 			}
 			catch (Exception e) {
@@ -194,7 +201,7 @@ private void validateCompletedTaskExitInformation(long executionId, Integer exit
 		Assert.notNull(endTime, "TaskExecution endTime cannot be null.");
 	}
 
-	private String trimMessage(String exitMessage, int maxSize) {
+	private @Nullable String trimMessage(@Nullable String exitMessage, int maxSize) {
 		String result = exitMessage;
 		if (exitMessage != null && exitMessage.length() > maxSize) {
 			result = exitMessage.substring(0, maxSize);
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/TaskExecutionDaoFactoryBean.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/TaskExecutionDaoFactoryBean.java
index f84920b0f..46d7706d0 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/TaskExecutionDaoFactoryBean.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/TaskExecutionDaoFactoryBean.java
@@ -22,6 +22,8 @@
 
 import javax.sql.DataSource;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.batch.infrastructure.item.database.support.DataFieldMaxValueIncrementerFactory;
 import org.springframework.batch.infrastructure.item.database.support.DefaultDataFieldMaxValueIncrementerFactory;
 import org.springframework.beans.factory.FactoryBean;
@@ -45,9 +47,9 @@
  */
 public class TaskExecutionDaoFactoryBean implements FactoryBean<TaskExecutionDao> {
 
-	private DataSource dataSource;
+	private @Nullable DataSource dataSource;
 
-	private TaskExecutionDao dao = null;
+	private @Nullable TaskExecutionDao dao;
 
 	private String tablePrefix = TaskProperties.DEFAULT_TABLE_PREFIX;
 
@@ -80,6 +82,7 @@ public TaskExecutionDaoFactoryBean(DataSource dataSource) {
 	}
 
 	@Override
+	@SuppressWarnings("NullAway")
 	public TaskExecutionDao getObject() throws Exception {
 		if (this.dao == null) {
 			if (this.dataSource != null) {
@@ -92,7 +95,9 @@ public TaskExecutionDao getObject() throws Exception {
 		if (this.dataSource != null) {
 			String databaseType = null;
 			try {
-				databaseType = DatabaseType.fromMetaData(dataSource).name();
+				DatabaseType dbType = DatabaseType.fromMetaData(dataSource);
+				Assert.state(dbType != null, "DatabaseType must not be null");
+				databaseType = dbType.name();
 			}
 			catch (MetaDataAccessException e) {
 				throw new IllegalStateException(e);
@@ -128,7 +133,9 @@ private void buildTaskExecutionDao(DataSource dataSource) {
 		this.dao = new JdbcTaskExecutionDao(dataSource, this.tablePrefix);
 		String databaseType;
 		try {
-			databaseType = DatabaseType.fromMetaData(dataSource).name();
+			DatabaseType dbType = DatabaseType.fromMetaData(dataSource);
+			Assert.state(dbType != null, "DatabaseType must not be null");
+			databaseType = dbType.name();
 		}
 		catch (MetaDataAccessException e) {
 			throw new IllegalStateException(e);
@@ -140,6 +147,7 @@ private void buildTaskExecutionDao(DataSource dataSource) {
 			.setTaskIncrementer(incrementerFactory.getIncrementer(databaseType, this.tablePrefix + "SEQ"));
 	}
 
+	@SuppressWarnings("NullAway")
 	private boolean isSqlServerTableSequenceAvailable(String incrementerName) {
 		boolean result = false;
 		DatabaseMetaData metaData = null;
@@ -155,7 +163,8 @@ private boolean isSqlServerTableSequenceAvailable(String incrementerName) {
 			}
 		}
 		catch (SQLException sqe) {
-			throw new TaskException(sqe.getMessage());
+			String message = sqe.getMessage();
+			throw new TaskException(message != null ? message : "SQL error occurred");
 		}
 		return result;
 	}
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/TaskRepositoryInitializer.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/TaskRepositoryInitializer.java
index a7e99bf3d..5f77ee124 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/TaskRepositoryInitializer.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/TaskRepositoryInitializer.java
@@ -18,6 +18,7 @@
 
 import java.sql.SQLException;
 import java.util.Locale;
+import java.util.Objects;
 
 import javax.sql.DataSource;
 
@@ -61,8 +62,10 @@ public final class TaskRepositoryInitializer implements InitializingBean {
 	 */
 	private static String schema = DEFAULT_SCHEMA_LOCATION;
 
+	@SuppressWarnings("NullAway.Init")
 	private DataSource dataSource;
 
+	@SuppressWarnings("NullAway.Init")
 	private ResourceLoader resourceLoader;
 
 	@Value("${spring.cloud.task.initialize.enable:true}")
@@ -85,7 +88,10 @@ public void setResourceLoader(ResourceLoader resourceLoader) {
 
 	private String getDatabaseType(DataSource dataSource) {
 		try {
-			return JdbcUtils.commonDatabaseName(DatabaseType.fromMetaData(dataSource).toString())
+			DatabaseType databaseType = DatabaseType.fromMetaData(dataSource);
+			String databaseTypeName = (databaseType != null) ? databaseType.toString() : null;
+			return Objects
+				.requireNonNull(JdbcUtils.commonDatabaseName(databaseTypeName), "Common database name is required")
 				.toLowerCase(Locale.ROOT);
 		}
 		catch (MetaDataAccessException ex) {
diff --git a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/package-info.java b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/package-info.java
index 74434a95f..5778354bc 100644
--- a/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/package-info.java
+++ b/spring-cloud-task-core/src/main/java/org/springframework/cloud/task/repository/support/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Classes used for setting up and supporting a task repositories.
  */
+@NullMarked
 package org.springframework.cloud.task.repository.support;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/EventEmittingItemProcessListener.java b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/EventEmittingItemProcessListener.java
index dccec1d6c..a4cf36e4b 100644
--- a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/EventEmittingItemProcessListener.java
+++ b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/EventEmittingItemProcessListener.java
@@ -18,6 +18,7 @@
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.batch.core.listener.ItemProcessListener;
 import org.springframework.batch.infrastructure.item.ItemProcessor;
@@ -69,7 +70,7 @@ public void beforeProcess(Object item) {
 	}
 
 	@Override
-	public void afterProcess(Object item, Object result) {
+	public void afterProcess(Object item, @Nullable Object result) {
 		if (result == null) {
 			this.messagePublisher.publish(this.properties.getItemProcessEventBindingName(), "1 item was filtered");
 		}
@@ -88,8 +89,9 @@ public void onProcessError(Object item, Exception e) {
 		if (logger.isDebugEnabled()) {
 			logger.debug("Executing onProcessError: " + e.getMessage(), e);
 		}
+		String message = e.getMessage();
 		this.messagePublisher.publishWithThrowableHeader(this.properties.getItemProcessEventBindingName(),
-				"Exception while item was being processed", e.getMessage());
+				"Exception while item was being processed", message != null ? message : e.getClass().getName());
 	}
 
 	@Override
diff --git a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/EventEmittingItemReadListener.java b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/EventEmittingItemReadListener.java
index 37dd3adb9..7dc23d7c0 100644
--- a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/EventEmittingItemReadListener.java
+++ b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/EventEmittingItemReadListener.java
@@ -75,9 +75,9 @@ public void onReadError(Exception ex) {
 		if (logger.isDebugEnabled()) {
 			logger.debug("Executing onReadError: " + ex.getMessage(), ex);
 		}
-
+		String message = ex.getMessage();
 		this.messagePublisher.publishWithThrowableHeader(this.properties.getItemReadEventBindingName(),
-				"Exception while item was being read", ex.getMessage());
+				"Exception while item was being read", message != null ? message : ex.getClass().getName());
 	}
 
 	@Override
diff --git a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/EventEmittingItemWriteListener.java b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/EventEmittingItemWriteListener.java
index 2f3db8726..15ee14605 100644
--- a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/EventEmittingItemWriteListener.java
+++ b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/EventEmittingItemWriteListener.java
@@ -83,8 +83,9 @@ public void onWriteError(Exception exception, Chunk items) {
 			logger.debug("Executing onWriteError: " + exception.getMessage(), exception);
 		}
 		String payload = "Exception while " + items.size() + " items are attempted to be written.";
+		String message = exception.getMessage();
 		this.messagePublisher.publishWithThrowableHeader(this.properties.getItemWriteEventBindingName(), payload,
-				exception.getMessage());
+				message != null ? message : exception.getClass().getName());
 	}
 
 	@Override
diff --git a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/EventEmittingSkipListener.java b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/EventEmittingSkipListener.java
index 22269dc4c..fdb1fc410 100644
--- a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/EventEmittingSkipListener.java
+++ b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/EventEmittingSkipListener.java
@@ -67,8 +67,9 @@ public void onSkipInRead(Throwable t) {
 		if (logger.isDebugEnabled()) {
 			logger.debug("Executing onSkipInRead: " + t.getMessage(), t);
 		}
+		String message = t.getMessage();
 		this.messagePublisher.publishWithThrowableHeader(this.properties.getSkipEventBindingName(),
-				"Skipped when reading.", t.getMessage());
+				"Skipped when reading.", message != null ? message : t.getClass().getName());
 	}
 
 	@Override
@@ -76,8 +77,9 @@ public void onSkipInWrite(Object item, Throwable t) {
 		if (logger.isDebugEnabled()) {
 			logger.debug("Executing onSkipInWrite: " + t.getMessage(), t);
 		}
+		String message = t.getMessage();
 		this.messagePublisher.publishWithThrowableHeader(this.properties.getSkipEventBindingName(), item,
-				t.getMessage());
+				message != null ? message : t.getClass().getName());
 	}
 
 	@Override
@@ -85,8 +87,9 @@ public void onSkipInProcess(Object item, Throwable t) {
 		if (logger.isDebugEnabled()) {
 			logger.debug("Executing onSkipInProcess: " + t.getMessage(), t);
 		}
+		String message = t.getMessage();
 		this.messagePublisher.publishWithThrowableHeader(this.properties.getSkipEventBindingName(), item,
-				t.getMessage());
+				message != null ? message : t.getClass().getName());
 	}
 
 	@Override
diff --git a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/package-info.java b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/package-info.java
index 15cf1adbb..fae184593 100644
--- a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/package-info.java
+++ b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Stream-based batch listener components for Spring Cloud Task.
  */
+@NullMarked
 package org.springframework.cloud.task.batch.listener;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/ExitStatus.java b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/ExitStatus.java
index afe27c4c9..e28d66204 100644
--- a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/ExitStatus.java
+++ b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/ExitStatus.java
@@ -16,6 +16,8 @@
 
 package org.springframework.cloud.task.batch.listener.support;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.util.Assert;
 
 /**
@@ -26,9 +28,9 @@
  */
 public class ExitStatus {
 
-	private String exitCode;
+	private @Nullable String exitCode;
 
-	private String exitDescription;
+	private @Nullable String exitDescription;
 
 	public ExitStatus() {
 	}
@@ -40,7 +42,7 @@ public ExitStatus(org.springframework.batch.core.ExitStatus exitStatus) {
 		this.exitDescription = exitStatus.getExitDescription();
 	}
 
-	public String getExitCode() {
+	public @Nullable String getExitCode() {
 		return this.exitCode;
 	}
 
@@ -48,7 +50,7 @@ public void setExitCode(String exitCode) {
 		this.exitCode = exitCode;
 	}
 
-	public String getExitDescription() {
+	public @Nullable String getExitDescription() {
 		return this.exitDescription;
 	}
 
diff --git a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/JobExecutionEvent.java b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/JobExecutionEvent.java
index 1893bbbd3..ae903a45f 100644
--- a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/JobExecutionEvent.java
+++ b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/JobExecutionEvent.java
@@ -25,6 +25,8 @@
 import java.util.Set;
 import java.util.concurrent.CopyOnWriteArrayList;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.batch.core.BatchStatus;
 import org.springframework.batch.core.Entity;
 import org.springframework.batch.core.job.JobExecution;
@@ -39,21 +41,21 @@
  */
 public class JobExecutionEvent extends Entity {
 
-	private JobParametersEvent jobParameters;
+	private @Nullable JobParametersEvent jobParameters;
 
-	private JobInstanceEvent jobInstance;
+	private @Nullable JobInstanceEvent jobInstance;
 
 	private Collection<StepExecutionEvent> stepExecutions = Collections.synchronizedList(new ArrayList<>());
 
 	private BatchStatus status = BatchStatus.STARTING;
 
-	private LocalDateTime startTime = null;
+	private @Nullable LocalDateTime startTime = null;
 
 	private LocalDateTime createTime = LocalDateTime.now();
 
-	private LocalDateTime endTime = null;
+	private @Nullable LocalDateTime endTime = null;
 
-	private LocalDateTime lastUpdated = null;
+	private @Nullable LocalDateTime lastUpdated = null;
 
 	private ExitStatus exitStatus = new ExitStatus(new org.springframework.batch.core.ExitStatus("UNKNOWN"));
 
@@ -85,26 +87,29 @@ public JobExecutionEvent(JobExecution original) {
 		this.exitStatus = new ExitStatus(original.getExitStatus());
 		this.executionContext = original.getExecutionContext();
 		this.failureExceptions = original.getFailureExceptions();
-		this.setVersion(original.getVersion());
+		Integer version = original.getVersion();
+		if (version != null) {
+			this.setVersion(version);
+		}
 	}
 
-	public JobParametersEvent getJobParameters() {
+	public @Nullable JobParametersEvent getJobParameters() {
 		return this.jobParameters;
 	}
 
-	public LocalDateTime getEndTime() {
+	public @Nullable LocalDateTime getEndTime() {
 		return this.endTime;
 	}
 
-	public void setEndTime(LocalDateTime endTime) {
+	public void setEndTime(@Nullable LocalDateTime endTime) {
 		this.endTime = endTime;
 	}
 
-	public LocalDateTime getStartTime() {
+	public @Nullable LocalDateTime getStartTime() {
 		return this.startTime;
 	}
 
-	public void setStartTime(LocalDateTime startTime) {
+	public void setStartTime(@Nullable LocalDateTime startTime) {
 		this.startTime = startTime;
 	}
 
@@ -134,7 +139,7 @@ public void upgradeStatus(BatchStatus status) {
 	 * Convenience getter for the id of the enclosing job. Useful for DAO implementations.
 	 * @return the id of the enclosing job
 	 */
-	public Long getJobId() {
+	public @Nullable Long getJobId() {
 		if (this.jobInstance != null) {
 			return this.jobInstance.getId();
 		}
@@ -158,11 +163,11 @@ public void setExitStatus(ExitStatus exitStatus) {
 	/**
 	 * @return the Job that is executing.
 	 */
-	public JobInstanceEvent getJobInstance() {
+	public @Nullable JobInstanceEvent getJobInstance() {
 		return this.jobInstance;
 	}
 
-	public void setJobInstance(JobInstanceEvent jobInstance) {
+	public void setJobInstance(@Nullable JobInstanceEvent jobInstance) {
 		this.jobInstance = jobInstance;
 	}
 
@@ -210,7 +215,7 @@ public void setCreateTime(LocalDateTime createTime) {
 	 * JobRepository.
 	 * @return Date representing the last time this JobExecution was updated.
 	 */
-	public LocalDateTime getLastUpdated() {
+	public @Nullable LocalDateTime getLastUpdated() {
 		return this.lastUpdated;
 	}
 
@@ -218,7 +223,7 @@ public LocalDateTime getLastUpdated() {
 	 * Set the last time this {@link JobExecution} was updated.
 	 * @param lastUpdated The date the {@link JobExecution} was updated.
 	 */
-	public void setLastUpdated(LocalDateTime lastUpdated) {
+	public void setLastUpdated(@Nullable LocalDateTime lastUpdated) {
 		this.lastUpdated = lastUpdated;
 	}
 
diff --git a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/JobInstanceEvent.java b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/JobInstanceEvent.java
index df98c41f3..f82c1edad 100644
--- a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/JobInstanceEvent.java
+++ b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/JobInstanceEvent.java
@@ -16,6 +16,8 @@
 
 package org.springframework.cloud.task.batch.listener.support;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.batch.core.Entity;
 import org.springframework.util.Assert;
 
@@ -29,7 +31,7 @@
 
 public class JobInstanceEvent extends Entity {
 
-	private String jobName;
+	private @Nullable String jobName;
 
 	public JobInstanceEvent() {
 		super(-1L);
@@ -44,7 +46,7 @@ public JobInstanceEvent(Long id, String jobName) {
 	/**
 	 * @return the job name. (Equivalent to getJob().getName())
 	 */
-	public String getJobName() {
+	public @Nullable String getJobName() {
 		return this.jobName;
 	}
 
diff --git a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/JobParameterEvent.java b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/JobParameterEvent.java
index 61a1baf2d..6ab555319 100644
--- a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/JobParameterEvent.java
+++ b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/JobParameterEvent.java
@@ -19,6 +19,8 @@
 import java.util.Date;
 import java.util.Objects;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.batch.core.job.parameters.JobParameter;
 
 /**
@@ -30,7 +32,7 @@
  */
 public class JobParameterEvent {
 
-	private Object parameter;
+	private @Nullable Object parameter;
 
 	private boolean identifying;
 
@@ -49,10 +51,10 @@ public boolean isIdentifying() {
 	/**
 	 * @return the value contained within this JobParameter.
 	 */
-	public Object getValue() {
+	public @Nullable Object getValue() {
 
-		if (this.parameter != null && this.parameter.getClass().isInstance(Date.class)) {
-			return new Date(((Date) this.parameter).getTime());
+		if (this.parameter instanceof Date dateParameter) {
+			return new Date((dateParameter).getTime());
 		}
 		else {
 			return this.parameter;
@@ -74,15 +76,15 @@ public boolean equals(Object obj) {
 	}
 
 	@Override
-	public String toString() {
-		return this.parameter == null ? null : this.parameter.toString();
+	public @Nullable String toString() {
+		return this.parameter == null ? "" : this.parameter.toString();
 	}
 
 	@Override
 	public int hashCode() {
 		final int BASE_HASH = 7;
 		final int MULTIPLIER_HASH = 21;
-		return BASE_HASH + MULTIPLIER_HASH * this.parameter.hashCode();
+		return BASE_HASH + MULTIPLIER_HASH * (this.parameter != null ? this.parameter.hashCode() : 0);
 	}
 
 }
diff --git a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/StepExecutionEvent.java b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/StepExecutionEvent.java
index 9a131641d..f9bc14242 100644
--- a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/StepExecutionEvent.java
+++ b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/StepExecutionEvent.java
@@ -20,6 +20,8 @@
 import java.util.List;
 import java.util.concurrent.CopyOnWriteArrayList;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.batch.core.BatchStatus;
 import org.springframework.batch.core.Entity;
 import org.springframework.batch.core.step.StepExecution;
@@ -37,7 +39,7 @@ public class StepExecutionEvent extends Entity {
 
 	private long jobExecutionId;
 
-	private String stepName;
+	private @Nullable String stepName;
 
 	private BatchStatus status = BatchStatus.STARTING;
 
@@ -55,11 +57,11 @@ public class StepExecutionEvent extends Entity {
 
 	private long writeSkipCount = 0;
 
-	private LocalDateTime startTime = LocalDateTime.now();
+	private @Nullable LocalDateTime startTime = LocalDateTime.now();
 
-	private LocalDateTime endTime = null;
+	private @Nullable LocalDateTime endTime = null;
 
-	private LocalDateTime lastUpdated = null;
+	private @Nullable LocalDateTime lastUpdated = null;
 
 	private ExecutionContext executionContext = new ExecutionContext();
 
@@ -145,7 +147,7 @@ public void setCommitCount(int commitCount) {
 	 * Returns the time that this execution ended.
 	 * @return the time that this execution ended
 	 */
-	public LocalDateTime getEndTime() {
+	public @Nullable LocalDateTime getEndTime() {
 		return this.endTime;
 	}
 
@@ -153,7 +155,7 @@ public LocalDateTime getEndTime() {
 	 * Sets the time that this execution ended.
 	 * @param endTime the time that this execution ended
 	 */
-	public void setEndTime(LocalDateTime endTime) {
+	public void setEndTime(@Nullable LocalDateTime endTime) {
 		this.endTime = endTime;
 	}
 
@@ -225,7 +227,7 @@ public void setFilterCount(int filterCount) {
 	 * Gets the time this execution started.
 	 * @return the time this execution started
 	 */
-	public LocalDateTime getStartTime() {
+	public @Nullable LocalDateTime getStartTime() {
 		return this.startTime;
 	}
 
@@ -233,7 +235,7 @@ public LocalDateTime getStartTime() {
 	 * Sets the time this execution started.
 	 * @param startTime the time this execution started
 	 */
-	public void setStartTime(LocalDateTime startTime) {
+	public void setStartTime(@Nullable LocalDateTime startTime) {
 		this.startTime = startTime;
 	}
 
@@ -256,11 +258,11 @@ public void setStatus(BatchStatus status) {
 	/**
 	 * @return the name of the step.
 	 */
-	public String getStepName() {
+	public @Nullable String getStepName() {
 		return this.stepName;
 	}
 
-	public void setStepName(String stepName) {
+	public void setStepName(@Nullable String stepName) {
 		this.stepName = stepName;
 	}
 
@@ -355,7 +357,7 @@ public void setProcessSkipCount(int processSkipCount) {
 	/**
 	 * @return the Date representing the last time this execution was persisted.
 	 */
-	public LocalDateTime getLastUpdated() {
+	public @Nullable LocalDateTime getLastUpdated() {
 		return this.lastUpdated;
 	}
 
@@ -363,7 +365,7 @@ public LocalDateTime getLastUpdated() {
 	 * Set the time when the StepExecution was last updated before persisting.
 	 * @param lastUpdated the {@link LocalDateTime} the StepExecution was last updated.
 	 */
-	public void setLastUpdated(LocalDateTime lastUpdated) {
+	public void setLastUpdated(@Nullable LocalDateTime lastUpdated) {
 		this.lastUpdated = lastUpdated;
 	}
 
@@ -389,8 +391,8 @@ public boolean equals(Object obj) {
 		}
 		StepExecution other = (StepExecution) obj;
 
-		return this.stepName.equals(other.getStepName()) && (this.jobExecutionId == other.getJobExecutionId())
-				&& getId() == other.getId();
+		return (this.stepName != null && this.stepName.equals(other.getStepName()))
+				&& (this.jobExecutionId == other.getJobExecutionId()) && getId() == other.getId();
 	}
 
 	/*
diff --git a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/TaskBatchEventListenerBeanPostProcessor.java b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/TaskBatchEventListenerBeanPostProcessor.java
index e98b6697a..cd9de74ba 100644
--- a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/TaskBatchEventListenerBeanPostProcessor.java
+++ b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/TaskBatchEventListenerBeanPostProcessor.java
@@ -18,6 +18,8 @@
 
 import java.lang.reflect.Field;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.aot.hint.MemberCategory;
 import org.springframework.aot.hint.RuntimeHints;
 import org.springframework.aot.hint.RuntimeHintsRegistrar;
@@ -42,6 +44,7 @@
 import org.springframework.cloud.task.batch.listener.support.TaskBatchEventListenerBeanPostProcessor.RuntimeHint;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.ImportRuntimeHints;
+import org.springframework.util.Assert;
 import org.springframework.util.ReflectionUtils;
 
 /**
@@ -88,13 +91,17 @@ public Object postProcessBeforeInitialization(Object bean, String beanName) thro
 
 				if (tasklet instanceof ChunkOrientedTasklet) {
 					Field chunkProviderField = ReflectionUtils.findField(ChunkOrientedTasklet.class, "chunkProvider");
+					Assert.state(chunkProviderField != null, "chunkProvider field must exist");
 					ReflectionUtils.makeAccessible(chunkProviderField);
 					SimpleChunkProvider chunkProvider = (SimpleChunkProvider) ReflectionUtils
 						.getField(chunkProviderField, tasklet);
 					Field chunkProcessorField = ReflectionUtils.findField(ChunkOrientedTasklet.class, "chunkProcessor");
+					Assert.state(chunkProcessorField != null, "chunkProcessor field must exist");
 					ReflectionUtils.makeAccessible(chunkProcessorField);
 					SimpleChunkProcessor chunkProcessor = (SimpleChunkProcessor) ReflectionUtils
 						.getField(chunkProcessorField, tasklet);
+					Assert.state(chunkProvider != null, "chunkProvider must not be null");
+					Assert.state(chunkProcessor != null, "chunkProcessor must not be null");
 					registerItemReadEvents(chunkProvider);
 					registerSkipEvents(chunkProvider);
 					registerItemProcessEvents(chunkProcessor);
@@ -176,7 +183,7 @@ private void registerStepExecutionEventListener(Object bean) {
 	static class RuntimeHint implements RuntimeHintsRegistrar {
 
 		@Override
-		public void registerHints(RuntimeHints hints, ClassLoader classLoader) {
+		public void registerHints(RuntimeHints hints, @Nullable ClassLoader classLoader) {
 			hints.reflection().registerType(ChunkOrientedTasklet.class, MemberCategory.DECLARED_FIELDS);
 		}
 
diff --git a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/package-info.java b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/package-info.java
index befb88e43..1b947e12a 100644
--- a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/package-info.java
+++ b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/batch/listener/support/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Support classes for stream-based batch listener components in Spring Cloud Task.
  */
+@NullMarked
 package org.springframework.cloud.task.batch.listener.support;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/listener/package-info.java b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/listener/package-info.java
index d6ee2ece4..1f4407970 100644
--- a/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/listener/package-info.java
+++ b/spring-cloud-task-stream/src/main/java/org/springframework/cloud/task/listener/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Stream-based task lifecycle listener support for Spring Cloud Task.
  */
+@NullMarked
 package org.springframework.cloud.task.listener;
+
+import org.jspecify.annotations.NullMarked;