Add ReactiveStreams and Kotlin Coroutines variants for DataLoader

[hantsy]

Spring Graphql added an variant for the reactive/webflux implementations. I hope the upstream project can consider ReactiveStreams API(Publisher) and Kotlin Couroutines(suspend fun or Flow) as alternatives of the existing return type( Java 8 CompletionStage) of a BatchLoader or MappedBatchLoader.

[bbakerman]

We dont support it because it would bring in a an extra dependencies.

However a CompletableFuture can be turned back into a Mono or Flow easily enough

[hantsy]

Java 9 add a Flow API to adapt ReactiveStreams, https://docs.oracle.com/javase/9/docs/api/java/util/concurrent/Flow.html

[bbakerman]

Yup and we are Java 8 based

[koenpunt]

@bbakerman you closed this as resolved, but I don't believe it really is?

[hantsy]

Almost all java libs and frameworks I used in projects are moved to Java 11 and Java 17, I think this data-loader project should catch up the main stream.