Removed the single writer callback executor from unit tests

Author: LBrandl

src/test/java/com/hivemq/persistence/SingleWriterServiceImplTest.java

@@ -101,10 +101,6 @@ public void stop_shutdownAllThreads() {
         singleWriterServiceImpl.stop();
         assertTrue(singleWriterServiceImpl.checkScheduler.isShutdown());
         assertTrue(singleWriterServiceImpl.singleWriterExecutor.isShutdown());
-
-        for (final ExecutorService callbackExecutor : singleWriterServiceImpl.callbackExecutors) {
-            assertTrue(callbackExecutor.isShutdown());
-        }
     }
 
     private static class NoOpExecutor implements ExecutorService {

src/test/java/util/TestSingleWriterFactory.java

@@ -15,7 +15,6 @@
  */
 package util;
 
-import com.google.common.util.concurrent.MoreExecutors;
 import com.hivemq.configuration.service.InternalConfigurations;
 import com.hivemq.persistence.SingleWriterService;
 import com.hivemq.persistence.SingleWriterServiceImpl;
@@ -34,9 +33,6 @@ public static SingleWriterService defaultSingleWriter() {
         InternalConfigurations.SINGLE_WRITER_INTERVAL_TO_CHECK_PENDING_TASKS_AND_SCHEDULE_MSEC.set(100);
 
         final SingleWriterServiceImpl singleWriterServiceImpl = new SingleWriterServiceImpl();
-        for (int i = 0; i < singleWriterServiceImpl.callbackExecutors.length; i++) {
-            singleWriterServiceImpl.callbackExecutors[i] = MoreExecutors.newDirectExecutorService();
-        }
 
         singleWriterServiceImpl.postConstruct();