You didn't want to couple your task to the Runnable interface, so instead you coupled it to an entire HTTP server? And in order to avoid the complexity of calling CompleteableFuture.runAsync, you're using an HTTP client? Could you explain in more detail how you think this is a simplification, because I don't get it?

ETA: I'm genuinely baffled by the proposed solution, and I struggled to phrase my comment in a way that didn't come off as confrontational. So please accept my apologies if it still appears overly negative; it's entirely possible I've not understood what your goals and constraints are.