Reports incorrect Micronaut Data repository method return types.

The following return types are supported:

void

Primitive types

Simple types

java.util.List or any common Iterable type

java.util.stream.Stream

java.util.Optional

io.micronaut.data.model.Page

io.micronaut.data.model.Slice

java.util.concurrent.Future or java.util.concurrent.CompletableFuture

A Reactive Streams compatible type, such as Publisher, Single, Maybe, Flux, Mono, and so on