GH-5234: fix limited programmatic configuration support of FedX source selection cache

[aschwarte10]

GitHub issue resolved: #5234

Add an additional constructor accepting a supplier for an initialized cache.

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[jetztgradnet]

LGTM. An additional constructor should not cause any binary incompatibilities.

[hmottestad]

This is a new feature though and not really a bug fix.

[aschwarte10]

This is a new feature though and not really a bug fix.

Technically, you are absolutely right, good eyes. Let me try to explain why I reported this as bug, which in our case impacts performance / stability of a federated system. For our use-cases more control over the cache strategies (eviction, size, introspection) is required to offer good performance.

If this change is not acceptable for a patch release, we in our case would (temporarily) need to override/customize some parts of the source selection logic to make the guava cache accessible. Please let me know.

[hmottestad]

We can change it from bug to performance and then we can include it.

[aschwarte10]

We can change it from bug to performance and then we can include it.

Thanks, I see that you already did this. Good to know!