[TrimmableTypeMap] Close scanner and JCW generator gaps vs legacy pipeline

src/Microsoft.Android.Sdk.TrimmableTypeMap/Generator/JcwJavaSourceGenerator.cs

@@ -85,6 +85,7 @@ internal void Generate (JavaPeerInfo type, TextWriter writer)
 		WriteClassDeclaration (type, writer);
 		WriteStaticInitializer (type, writer);
 		WriteConstructors (type, writer);
+		WriteFields (type, writer);
 		WriteMethods (type, writer);
 		WriteGCUserPeerMethods (writer);
 		WriteClassClose (writer);
@@ -181,6 +182,28 @@ static void WriteConstructors (JavaPeerInfo type, TextWriter writer)
 		}
 	}
 
+	static void WriteFields (JavaPeerInfo type, TextWriter writer)
+	{
+		foreach (var field in type.JavaFields) {
+			writer.Write ('\t');
+			writer.Write (field.Visibility);
+			writer.Write (' ');
+			if (field.IsStatic) {
+				writer.Write ("static ");
+			}
+			writer.Write (field.JavaTypeName);
+			writer.Write (' ');
+			writer.Write (field.FieldName);
+			writer.Write (" = ");
+			writer.Write (field.InitializerMethodName);
+			writer.WriteLine (" ();");
+		}
+
+		if (type.JavaFields.Count > 0) {
+			writer.WriteLine ();
+		}
+	}
+
 	static void WriteMethods (JavaPeerInfo type, TextWriter writer)
 	{
 		foreach (var method in type.MarshalMethods) {
@@ -214,13 +237,14 @@ static void WriteMethods (JavaPeerInfo type, TextWriter writer)
 
 """);
 			} else {
+				string access = method.IsExport && method.JavaAccess != null ? method.JavaAccess : "public";
 				writer.Write ($$"""
 
-	public {{javaReturnType}} {{method.JniName}} ({{parameters}}){{throwsClause}}
+	{{access}} {{javaReturnType}} {{method.JniName}} ({{parameters}}){{throwsClause}}
 	{
 		{{returnPrefix}}{{method.NativeCallbackName}} ({{args}});
 	}
-	public native {{javaReturnType}} {{method.NativeCallbackName}} ({{parameters}});
+	{{access}} native {{javaReturnType}} {{method.NativeCallbackName}} ({{parameters}});
 
 """);
 			}

src/Microsoft.Android.Sdk.TrimmableTypeMap/Scanner/JavaPeerInfo.cs

@@ -86,6 +86,12 @@ sealed record JavaPeerInfo
 	/// </summary>
 	public IReadOnlyList<JavaConstructorInfo> JavaConstructors { get; init; } = [];
 
+	/// <summary>
+	/// Java fields from [ExportField] attributes.
+	/// Each field is initialized by calling the annotated method.
+	/// </summary>
+	public IReadOnlyList<JavaFieldInfo> JavaFields { get; init; } = [];
+
 	/// <summary>
 	/// Information about the activation constructor for this type.
 	/// May reference a base type's constructor if the type doesn't define its own.
@@ -159,6 +165,19 @@ sealed record MarshalMethodInfo
 	/// </summary>
 	public bool IsConstructor { get; init; }
 
+	/// <summary>
+	/// True if this method comes from an [Export] attribute (rather than [Register]).
+	/// [Export] methods use the C# method's access modifier in the JCW Java file
+	/// instead of always being "public".
+	/// </summary>
+	public bool IsExport { get; init; }
+
+	/// <summary>
+	/// Java access modifier for [Export] methods ("public", "protected", "private").
+	/// Null for [Register] methods (always "public").
+	/// </summary>
+	public string? JavaAccess { get; init; }
+
 	/// <summary>
 	/// For [Export] methods: Java exception types that the method declares it can throw.
 	/// Null for [Register] methods.
@@ -210,6 +229,38 @@ sealed record JavaConstructorInfo
 	public string? SuperArgumentsString { get; init; }
 }
 
+/// <summary>
+/// Describes a Java field from an [ExportField] attribute.
+/// The field is initialized by calling the annotated method.
+/// </summary>
+sealed record JavaFieldInfo
+{
+	/// <summary>
+	/// Java field name, e.g., "STATIC_INSTANCE".
+	/// </summary>
+	public required string FieldName { get; init; }
+
+	/// <summary>
+	/// Java type name for the field, e.g., "java.lang.String".
+	/// </summary>
+	public required string JavaTypeName { get; init; }
+
+	/// <summary>
+	/// Name of the method that initializes this field, e.g., "GetInstance".
+	/// </summary>
+	public required string InitializerMethodName { get; init; }
+
+	/// <summary>
+	/// Java access modifier ("public", "protected", "private").
+	/// </summary>
+	public required string Visibility { get; init; }
+
+	/// <summary>
+	/// Whether the field is static.
+	/// </summary>
+	public bool IsStatic { get; init; }
+}
+
 /// <summary>
 /// Describes how to call the activation constructor for a Java peer type.
 /// </summary>