@Override
        public void channelActive(ChannelHandlerContext ctx) throws Exception {
            DefaultFullHttpRequest upgradeRequest = new DefaultFullHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.GET,
                "/");
            ctx.writeAndFlush(upgradeRequest);

            ctx.fireChannelActive();

            // Done with this handler, remove it from the pipeline.
            ctx.pipeline().remove(this);

            configureEndOfPipeline(ctx.pipeline());
        }
A handler that triggers the cleartext upgrade to HTTP/2 by sending an initial
HTTP request.
remoting/remoting-http/src/main/java/com/alipay/sofa/rpc/transport/http/Http2ClientInitializer.java