What

Currently the providers (e.g. RealmProvider, ClientProvider) accessible (in)directly from KeycloakSession operate on List and similar collections.

Consequently, the List operations are realized in memory even when only needed temporarily to be later filtered out like in this piece of code.

Thus the stream variants of the methods should be created, with backward compatibility in mind.

This epic spans from the lowest JPA layer up to REST endpoints which should return Stream<T> instead of List<T>. Using StreamingOutput might be a more performant option for the streamed data.

Acceptance criteria

• All interfaces mentioned above have Stream counterparts for operations that currently operate on collections
• REST endpoints preferentially use Stream<T> over the current collections
• JPA preferentially use streams for obtaining query results where applicable