Revert "refactor: JMeterSerialTest to Kotlin so we have one less compileJava task"

This reverts commit 1c64012.

Author: vlsi

src/jorphan/src/testFixtures/kotlin/org/apache/jorphan/test/JMeterSerialTest.kt

@@ -15,16 +15,17 @@
  * limitations under the License.
  */
 
-package org.apache.jorphan.test
+package org.apache.jorphan.test;
 
-import org.junit.jupiter.api.parallel.Execution
-import org.junit.jupiter.api.parallel.ExecutionMode
-import org.junit.jupiter.api.parallel.Isolated
+import org.junit.jupiter.api.parallel.Execution;
+import org.junit.jupiter.api.parallel.ExecutionMode;
+import org.junit.jupiter.api.parallel.Isolated;
 
 /**
  * Used to tag tests which need to be run on their own (in serial) because
  * either, they cause other tests to fail, or they fail when run in parallel.
  */
 @Isolated
 @Execution(ExecutionMode.SAME_THREAD)
-interface JMeterSerialTest
+public interface JMeterSerialTest {
+}