@Override
        public void done() {
          // must switch after sending the connection header response, as the client still uses the
          // original SaslClient to unwrap the data we send back
          saslServer.switchToCryptoAES(pair.getSecond());
        }
Send the response for connection header
hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/ServerRpcConnection.java