code: public static ChannelUDT channelUDT(final Channel channel) {
          // bytes
          if (channel instanceof NioUdtByteAcceptorChannel) {
              return ((NioUdtByteAcceptorChannel) channel).javaChannel();
          }
          if (channel instanceof NioUdtByteRendezvousChannel) {
              return ((NioUdtByteRendezvousChannel) channel).javaChannel();
          }
          if (channel instanceof NioUdtByteConnectorChannel) {
              return ((NioUdtByteConnectorChannel) channel).javaChannel();
          }
  
          // message
          if (channel instanceof NioUdtMessageAcceptorChannel) {
              return ((NioUdtMessageAcceptorChannel) channel).javaChannel();
          }
          if (channel instanceof NioUdtMessageRendezvousChannel) {
              return ((NioUdtMessageRendezvousChannel) channel).javaChannel();
          }
          if (channel instanceof NioUdtMessageConnectorChannel) {
              return ((NioUdtMessageConnectorChannel) channel).javaChannel();
          }
  
          return null;
      }
docs: Expose underlying {@link ChannelUDT} for debugging and monitoring.
  <p>
  @return underlying {@link ChannelUDT} or null, if parameter is not
  {@link UdtChannel}