I hate the fucking Spring WebFlux and the goddamn Project Reactor on which it depends!
Even debugging a simple CRUD microservice with simple business logic is such a pain in the ass, exception handling has a lot of "magic" implicit stuff which makes me waste hours in fucking trial & error and I have to use very little breakpoints because if a request is paused for more than few seconds it gets terminated.
I love functional programming but why shove it in fucking Java making me waste 90% of my time in trying to guessing what the fucking framework is doing, why not just use Scala which runs in the JVM? We don't even need compatibility with legacy code since it's a greenfield project!

And before you ask yes, I read a fucking book about Project Reactor and Java reactive programming and a lot of docs on Spring, Spring Boot and Spring Web Flux.