Fix compilation error and modernize

[gewarren]

(Hide whitespace changes.)

Compilation error introduced by https://github.com/dotnet/dotnet-api-docs/pull/8741 (by me).

[dotnet-issue-labeler[bot]]

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[learn-build-service-prod[bot]]

Learn Build status updates of commit 4c49642:

:warning: Validation status: warnings

File	Status	Preview URL	Details
xml/System.Collections.Generic/CollectionExtensions.xml	:warning:Warning	View	Details
snippets/csharp/Microsoft.Win32.SafeHandles/SafeWaitHandle/Overview/Project.csproj	:white_check_mark:Succeeded
snippets/csharp/Microsoft.Win32.SafeHandles/SafeWaitHandle/Overview/sample.cs	:white_check_mark:Succeeded	View
xml/Microsoft.Win32.SafeHandles/SafeWaitHandle.xml	:white_check_mark:Succeeded	View

xml/System.Collections.Generic/CollectionExtensions.xml

• [Warning: file-not-redirected - See documentation] File xml/System.Collections.Generic/CollectionExtensions.xml with URL /dotnet/api/system.collections.generic.collectionextensions.getdefaultassets was deleted without redirection. To avoid broken links, add a redirection.
• [Warning: file-not-redirected - See documentation] File xml/System.Collections.Generic/CollectionExtensions.xml with URL /dotnet/api/system.collections.generic.collectionextensions.getdefaultgroup was deleted without redirection. To avoid broken links, add a redirection.
• [Warning: file-not-redirected - See documentation] File xml/System.Collections.Generic/CollectionExtensions.xml with URL /dotnet/api/system.collections.generic.collectionextensions.getdefaultruntimefileassets was deleted without redirection. To avoid broken links, add a redirection.
• [Warning: file-not-redirected - See documentation] File xml/System.Collections.Generic/CollectionExtensions.xml with URL /dotnet/api/system.collections.generic.collectionextensions.getruntimeassets was deleted without redirection. To avoid broken links, add a redirection.
• [Warning: file-not-redirected - See documentation] File xml/System.Collections.Generic/CollectionExtensions.xml with URL /dotnet/api/system.collections.generic.collectionextensions.getruntimefileassets was deleted without redirection. To avoid broken links, add a redirection.
• [Warning: file-not-redirected - See documentation] File xml/System.Collections.Generic/CollectionExtensions.xml with URL /dotnet/api/system.collections.generic.collectionextensions.getruntimegroup was deleted without redirection. To avoid broken links, add a redirection.

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