@Override
        public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
            if (needsToFilterUpgradeRequest) {
                needsToFilterUpgradeRequest = false;
                final FullHttpRequest req = (FullHttpRequest) msg;
                req.headers().set(HttpHeaderNames.CONNECTION, CONNECTION_VALUE);

                if (!needsToFilterUpgradeResponse) {
                    ctx.pipeline().remove(this);
                }
            }

            super.write(ctx, msg, promise);
        }
Workaround handler for interoperability with Jetty.
- Jetty performs case-sensitive comparison for the Connection header value. (upgrade vs Upgrade)
- Jetty does not send 'Upgrade: h2c' header in its 101 Switching Protocol response.
core/src/main/java/com/linecorp/armeria/client/HttpClientPipelineConfigurator.java