@Override
  public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
    CompletableFuture<ByteBuf> promise = ctx.channel().attr(Http2BlockingChannel.RESPONSE_PROMISE).getAndSet(null);
    if (promise != null) {
      promise.completeExceptionally(cause);
      releaseStreamChannel(ctx);
    }
  }
Netty handler for {@link Http2BlockingChannel} to handle {@link FullHttpResponse}.
ambry-network/src/main/java/com/github/ambry/network/http2/Http2BlockingChannelResponseHandler.java