@Override
      protected NettyServerRpcConnection createNettyServerRpcConnection(Channel channel) {
        conn.set(super.createNettyServerRpcConnection(channel));
        return conn.get();
      }
This test is for HBASE-27923,which NettyRpcServer may hange if it should skip initial sasl
handshake.
hbase-server/src/test/java/org/apache/hadoop/hbase/ipc/TestRpcSkipInitialSaslHandshake.java