docs: @Internal
      public static NettyMutableHttpResponse getOr(NettyHttpRequest<?> request, io.micronaut.http.HttpResponse<?> alternative) {
          Attribute<NettyMutableHttpResponse> attr = request.attr(KEY);
          NettyMutableHttpResponse nettyHttpResponse = attr.get();
          if (nettyHttpResponse == null) {
              nettyHttpResponse = (NettyMutableHttpResponse) alternative;
              attr.set(nettyHttpResponse);
          }
          return nettyHttpResponse;
      }