private void waitForOperationsStarted() throws InterruptedException {
      operationStartedLatch.await(TIMEOUT_SECONDS, SECONDS);

    }
NOTE: do not replace createPartitionedRegionRunnable with lambda
because ResourceObserverAdapter is NOT serializable
geode-core/src/distributedTest/java/org/apache/geode/internal/cache/control/RebalanceOperationDistributedTest.java