@Override
    public void postDisableTable(ObserverContext<MasterCoprocessorEnvironment> ctx, TableName tn) {
      postHookCalls.incrementAndGet();
    }
Tests class that validates that "post" observer hook methods are only invoked when the operation
was successful.
hbase-server/src/test/java/org/apache/hadoop/hbase/master/procedure/TestMasterObserverPostCalls.java