feat(benchmark): add JMH benchmark for Topic.doMessageSend() lock contention

Author: jeanouii

activemq-unit-tests/pom.xml

@@ -278,6 +278,20 @@
       <artifactId>mockito-core</artifactId>
       <scope>test</scope>
     </dependency>
+
+    <!-- JMH for micro-benchmarks (excluded from CI via naming convention) -->
+    <dependency>
+      <groupId>org.openjdk.jmh</groupId>
+      <artifactId>jmh-core</artifactId>
+      <version>1.37</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.openjdk.jmh</groupId>
+      <artifactId>jmh-generator-annprocess</artifactId>
+      <version>1.37</version>
+      <scope>test</scope>
+    </dependency>
   </dependencies>
 
   <reporting>