Remove `!` from `Microsoft.Extensions.Caching.Abstractions`

[maxkoshevoi]

This is a blanket issue for all ! operations that were added in #64018
They should be removed or reviewed.

Left to be fixed/reviewed:

• [Group 2] Enable nullable annotations for Microsoft.Extensions.Caching.Abstractions #64018 (comment) (40d8838)

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

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Issue Details

---

This is a blanket issue for all ! operations that were added in #64018
They should be removed or reviewed.

Left to be fixed/reviewed:

• [Group 2] Enable nullable annotations for Microsoft.Extensions.Caching.Abstractions #64018 (comment)

Author:	maxkoshevoi
Assignees:	-
Labels:	untriaged, area-Extensions-Caching
Milestone:	-

[hrrrrustic]

@eerhardt There is only one ! left that was discussed in initial PR #64018 (comment)

runtime/src/libraries/Microsoft.Extensions.Caching.Abstractions/src/CacheEntryExtensions.cs

Lines 175 to 178 in b9b5fef

	foreach (PostEvictionCallbackRegistration postEvictionCallback in options.PostEvictionCallbacks)
	{
	entry.RegisterPostEvictionCallback(postEvictionCallback.EvictionCallback!, postEvictionCallback.State);
	}

I don't think it's a bug because it doesn't make any sense to register null callbacks. Is it fine to just add null-check (with throwing) before invocation and remove last !?

[eerhardt]

Yes, I think that is a fine solution here. Check if it EvictionCallback is null, and throw an exception here saying it can't be null.