Allow use of GraphQL Java 21.x with Spring for GraphQL 1.3.x

[rstoyanchev]

The EMPTY_DATA_LOADER_REGISTRY constant moved from DataLoaderDispatcherInstrumentationState (removed in 22) to EmptyDataLoaderRegistryInstance (added in 22). While 1.3 has GraphQL Java 22 as a baseline, it's not too difficult to remove this one obstacle to at least being able to run with 21.

[rstoyanchev]

Re-opening to fix in 1.2.x as well.

[rstoyanchev]

Nope, re-opened wrong issue.