Add missing API documentation for Microsoft.Extensions.FileProvider

[Copilot]

• Fix ActiveChangeCallbacks property summary (incorrectly said "always false")
• Fix class-level remarks (incorrectly said "does not raise any change callbacks")

Original prompt

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This section details on the original issue you should resolve

<issue_title>API documentation debt - Microsoft.Extensions.FileProvider</issue_title>
<issue_description>Area owners: @maryamariyan @carlossanlop @jozkee

The APIs in the list below are missing some or all of their documentation. Please add the missing documentation directly in triple slash comments in source. We will make sure it gets ported to dotnet-api-docs after it's merged.

Make sure to follow the documentation guidelines defined in the dotnet-api-docs wiki:
https://github.com/dotnet/dotnet-api-docs/wiki

Also please add me as a PR reviewer.

Community contributions are welcome.

Microsoft.Extensions.FileProviders

DocId	Summary	Parameters	TypeParameters	ReturnValue	Source File Path	Docs URL
Microsoft.Extensions.FileProviders.Physical namespace	Missing	NA	NA	NA	https://github.com/dotnet/dotnet-api-docs/blob/master/xml/ns-Microsoft.Extensions.FileProviders.Physical.xml	https://review.docs.microsoft.com/en-us/dotnet/api/Microsoft.Extensions.FileProviders.Physical?branch=master
Microsoft.Extensions.FileProviders.Composite namespace	Missing	NA	NA	NA	https://github.com/dotnet/dotnet-api-docs/blob/master/xml/ns-Microsoft.Extensions.FileProviders.Composite.xml	https://review.docs.microsoft.com/en-us/dotnet/api/Microsoft.Extensions.FileProviders.Composite?branch=master
Microsoft.Extensions.FileProviders namespace	Missing	NA	NA	NA	https://github.com/dotnet/dotnet-api-docs/blob/master/xml/ns-Microsoft.Extensions.FileProviders.xml	https://review.docs.microsoft.com/en-us/dotnet/api/Microsoft.Extensions.FileProviders?branch=master
M:Microsoft.Extensions.FileProviders.NullFileProvider.#ctor	Missing	NA	NA	NA	https://github.com/dotnet/dotnet-api-docs/blob/master/xml/Microsoft.Extensions.FileProviders/NullFileProvider.xml	https://review.docs.microsoft.com/en-us/dotnet/api/Microsoft.Extensions.FileProviders.NullFileProvider.-ctor?branch=master
M:Microsoft.Extensions.FileProviders.NotFoundDirectoryContents.#ctor	Missing	NA	NA	NA	https://github.com/dotnet/dotnet-api-docs/blob/master/xml/Microsoft.Extensions.FileProviders/NotFoundDirectoryContents.xml	https://review.docs.microsoft.com/en-us/dotnet/api/Microsoft.Extensions.FileProviders.NotFoundDirectoryContents.-ctor?branch=master
M:Microsoft.Extensions.FileProviders.FileSystemInfoHelper.#ctor	Missing	NA	NA	NA	https://github.com/dotnet/dotnet-api-docs/blob/master/xml/Microsoft.Extensions.FileProviders/FileSystemInfoHelper.xml	https://review.docs.microsoft.com/en-us/dotnet/api/Microsoft.Extensions.FileProviders.FileSystemInfoHelper.-ctor?branch=master

Notes:

• The namespaces need to be documented directly in dotnet-api-docs.
• Some of the APIs are obsolete, so I'll let area owners decide if they want to still document them or skip them. If you opt for documenting them, please do it directly in dotnet-api-docs.</issue_description>

<agent_instructions>Add XML documentation for the members mentioned in the issue that still don't have it.</agent_instructions>

Comments on the Issue (you are @copilot in this section)

@ Tagging subscribers to this area: @maryamariyan See info in area-owners.md if you want to be subscribed.

• Fixes API documentation debt - Microsoft.Extensions.FileProvider #43900

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[svick]

cc: @carlossanlop, in case you're still interested

[Copilot]

Pull request overview

This PR updates XML documentation across the Microsoft.Extensions.FileProviders.* implementations to use more consistent constructor phrasing and clearer parameter descriptions, and adds explicit parameterless constructors where documentation is now provided.

Changes:

• Standardize constructor XML docs to “Initializes a new instance of the … class …”.
• Clarify several parameter descriptions (e.g., filters, disposing, and callback/state parameters).
• Add explicit parameterless constructors (with docs) for NullFileProvider and NotFoundDirectoryContents.

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/libraries/Microsoft.Extensions.FileProviders.Physical/src/PollingWildCardChangeToken.cs	Constructor XML doc phrasing standardized.
src/libraries/Microsoft.Extensions.FileProviders.Physical/src/PollingFileChangeToken.cs	Constructor XML doc standardized; callback/state param docs updated.
src/libraries/Microsoft.Extensions.FileProviders.Physical/src/PhysicalFilesWatcher.cs	Constructor/parameter XML docs clarified and standardized.
src/libraries/Microsoft.Extensions.FileProviders.Physical/src/PhysicalFileProvider.cs	Constructor/parameter XML docs clarified and standardized.
src/libraries/Microsoft.Extensions.FileProviders.Physical/src/PhysicalFileInfo.cs	Constructor XML doc phrasing standardized.
src/libraries/Microsoft.Extensions.FileProviders.Physical/src/PhysicalDirectoryInfo.cs	Constructor XML doc phrasing standardized.
src/libraries/Microsoft.Extensions.FileProviders.Physical/src/Internal/PhysicalDirectoryContents.cs	Constructor/parameter XML docs clarified and standardized.
src/libraries/Microsoft.Extensions.FileProviders.Composite/src/CompositeDirectoryContents.cs	Constructor XML doc grammar adjusted and standardized.
src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NullFileProvider.cs	Adds explicit parameterless constructor with XML docs.
src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NotFoundFileInfo.cs	Constructor XML doc phrasing standardized.
src/libraries/Microsoft.Extensions.FileProviders.Abstractions/src/NotFoundDirectoryContents.cs	Adds explicit parameterless constructor with XML docs.

[Copilot]

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated 1 comment.