skip version5 tests on jdk8

Author: laurit

instrumentation/vertx/vertx-rx-java-3.5/javaagent/build.gradle.kts

@@ -85,6 +85,18 @@ testing {
 }
 
 tasks {
+  named("compileVersion5TestJava", JavaCompile::class).configure {
+    options.release.set(11)
+  }
+  val testJavaVersion =
+    gradle.startParameter.projectProperties.get("testJavaVersion")?.let(JavaVersion::toVersion)
+      ?: JavaVersion.current()
+  if (!testJavaVersion.isCompatibleWith(JavaVersion.VERSION_11)) {
+    named("version5Test", Test::class).configure {
+      enabled = false
+    }
+  }
+
   check {
     dependsOn(testing.suites)
   }