The problem is (IMHO) that org.springframework.data.jpa.repository.EntityGraph is marked as a @QueryAnnotation.
The purpose of @QueryAnnotation is to mark store specific @Query annotations like the ones in SD Mongo DB and SD JPA.
This leads to the fact that the overridden method gets enlisted in the "queryMethods" within org.springframework.data.repository.core.support.DefaultRepositoryInformation.getQueryMethods() since the check for a @QueryAnnotation in isQueryMethodCandidate returns true in this case.
This triggers the configured CreateIfNotFoundQueryLookupStrategy to try to lookup a named query named 'findAll' which doesn't exist...
If we'd simply remove the @QueryAnnotation from @EntityGraph then the correct method will be invoked, but the @EntityGraph configuration is not applied.
Hm, findOne(…) is a bit tricky as we're currently not issuing a query for the execution but rather use special EntityManager APIs for that (i.e. em.find(…)). Michael Simons - would you mind to create a separate ticket for that?