@Override
    public void rebalancingStarted(Region region) {
      super.rebalancingStarted(region);
      checkAllRegionRecoveryOrRebalanceStarted(region.getName());
    }
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