@Override
        protected void decode(ChannelHandlerContext ctx, ByteBuf buffer, List<Object> out) throws Exception {
            final int oldSize = out.size();
            super.decode(ctx, buffer, out);
            final int size = out.size();
            for (int i = oldSize; i < size; i++) {
                final Object obj = out.get(i);
                if (obj instanceof HttpRequest) {
                    queue.add(((HttpRequest) obj).method());
                }
            }
        }
Upgrades to another protocol from HTTP. Removes the {@link HttpRequestDecoder} and
{@link HttpResponseEncoder} from the pipeline.
core/src/main/java/com/linecorp/armeria/server/HttpServerCodec.java