Add JMH annotation processing for JDK-20+ sources

Signed-off-by: Andriy Redko <[email protected]>

benchmarks/build.gradle

@@ -105,10 +105,12 @@ if (BuildParams.runtimeJavaVersion >= JavaVersion.VERSION_20) {
   dependencies {
     java20Implementation sourceSets.main.output
     java20Implementation project(':libs:opensearch-common').sourceSets.java20.output
+    java20AnnotationProcessor "org.openjdk.jmh:jmh-generator-annprocess:$versions.jmh"
   }
 
   compileJava20Java {
     targetCompatibility = JavaVersion.VERSION_20
+    options.compilerArgs.addAll(["-processor", "org.openjdk.jmh.generators.BenchmarkProcessor"])
   }
 
   jar {
@@ -118,4 +120,7 @@ if (BuildParams.runtimeJavaVersion >= JavaVersion.VERSION_20) {
     }
     manifest.attributes('Multi-Release': 'true')
   }
+
+  // classes generated by JMH can use all sorts of forbidden APIs but we have no influence at all and cannot exclude these classes
+  disableTasks('forbiddenApisJava20')
 }