code: protected void handleOversizedMessage(ChannelHandlerContext ctx, S oversized) throws Exception {
          ctx.fireExceptionCaught(
                  new TooLongFrameException("content length exceeded " + maxContentLength() + " bytes."));
      }
docs: Invoked when an incoming request exceeds the maximum content length.  The default behvaior is to trigger an
  {@code exceptionCaught()} event with a {@link TooLongFrameException}.
  
  @param ctx the {@link ChannelHandlerContext}
  @param oversized the accumulated message up to this point, whose type is {@code S} or {@code O}