I see what you mean. Seeing it this way we’re not truly asynchronous because we need the response of the external services to answer the request. But at least every I/O in our webserver is async, so that it doesn’t completely block a Jetty thread.
The only other way that I know of to be truly async is to let the webserver respond very quickly to the request, then deliver the true response through web sockets or server sent events. It’s a technique pioneered by LinkedIn I think.