@Override
      CompletableFuture<MasterService.Interface> getMasterStub() {
        return CompletableFuture.completedFuture(masterStub);
      }
Confirm that we will set the priority in {@link HBaseRpcController} for several admin operations.
hbase-client/src/test/java/org/apache/hadoop/hbase/client/TestAsyncAdminRpcPriority.java