@SuppressWarnings("FutureReturnValueIgnored")
      @Override
      public Void answer(InvocationOnMock invocation) throws Throwable {
        threadPool.submit(() -> {
          ScanRequest req = invocation.getArgument(1);
          RpcCallback<ScanResponse> done = invocation.getArgument(2);
          assertTrue("close request should have scannerId", req.hasScannerId());
          assertEquals("close request's scannerId should match", scannerId, req.getScannerId());
          assertTrue("close request should have closerScanner set",
            req.hasCloseScanner() && req.getCloseScanner());

          done.run(ScanResponse.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