@Override
      public Void answer(InvocationOnMock invocation) throws Throwable {
        RpcCallback<GetResponse> done = invocation.getArgument(2);
        done.run(GetResponse.getDefaultInstance());
        return null;
      }
Confirm that we will set the priority in {@link HBaseRpcController} for several table operations.
hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestAsyncTableRpcPriority.java