[0.64] Fix nonnull compat issue

[HeyImChris]

Please select one of the following

• I am making a change required for Microsoft usage of react-native

Summary

Some downstream dependencies have non null checks that fail here if we don't tag appropriately. This is also a virtuous change as it adds clarity to the method header.

Changelog

[Bug] [iOS/macOS] - Nonnull compatibility check

Test Plan

No functional change

[pull-bot]

	Warnings
⚠️	❔ Base Branch - The base branch for this PR is something other than master. Are you sure you want to merge these changes into a stable release? If you are interested in backporting updates to an older release, the suggested approach is to land those changes on master first and then cherry-pick the commits into the branch for that release. The Releases Guide has more information.

Messages

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📋 Verify Changelog Format - A changelog entry has the following format: [CATEGORY] [TYPE] - Message. CATEGORY may be: General macOS iOS Android JavaScript Internal (for changes that do not need to be called out in the release notes) TYPE may be: Added, for new features. Changed, for changes in existing functionality. Deprecated, for soon-to-be removed features. Removed, for now removed features. Fixed, for any bug fixes. Security, in case of vulnerabilities. MESSAGE may answer "what and why" on a feature level. Use this to briefly tell React Native users about notable changes.

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