Add support for RxJava 3 [DATACMNS-1653]

[spring-projects-issues]

Mark Paluch opened DATACMNS-1653 and commented

We should add support for RxJava 3 to use reactive repositories using RxJava 3 types

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Reference URL: spring-projects/spring-framework#24170

Issue Links:

• DATAMONGO-2558 Add integration test for RxJava 3 repositories
  ("is depended on by")

Referenced from: pull request #444