code: @SuppressWarnings("WeakerAccess")
      protected void onExceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
          logger.debug("Exception caught: {}", cause.getMessage(), cause);
      }
docs: Logs the exception on DEBUG level.
  <p>
  Subclasses may override to customize logging behavior.
  
  @param ctx   the {@link ChannelHandlerContext}.
  @param cause the exception that was caught.