Description

Refactors bothCopyOnWriteList andWeakReferenceList as generic type-safe collections.

• Theoretically, they could have been merged into one but I chose not to currently.

Both lists now support initialization with capacity argument, previously integers passed in (e.g. inPropagateParentOwners) would end up being boxed and the instance of the box being used as a lock. This clearly feels like a mistake.

InResourceDictionaryDiagnostics I've removed few static fields caching empty (readonly) arrays I didn' see in#10267.

Regarding the removed null-checks:

• Those are a part of theas casting pattern.
• The enumerator returns strong, non-null references, hence it will never benull in the first place.
• I've appropriately null-annotated the adjusted files.

SinceContainsOwner is only called from within the three classes, we can remove the type checks and speed it up.

• Similarly it can be done for Add/Remove but I'll do that after this is in.

Customer Impact

Improved performance a tiny bit, strongly-typed code and newer practices.

Regression

No.

Testing

Local build, unit tests, testing with sample apps including themes and templates.

Risk

Low to medium, I believe the changes are straightforward and understandable but happy to answer any questions (rather sooner than later).

Microsoft Reviewers:Open in CodeFlow