Obsolete ServicePointManager 🎉

[MihaZupan]

Closes #71836

[dotnet-issue-labeler]

Note regarding the new-api-needs-documentation label:

This serves as a reminder for when your PR is modifying a ref *.cs file and adding/modifying public APIs, please make sure the API implementation in the src *.cs file is documented with triple slash comments, so the PR reviewers can sign off that change.

[dotnet-issue-labeler]

Note regarding the new-api-needs-documentation label:

This serves as a reminder for when your PR is modifying a ref *.cs file and adding/modifying public APIs, please make sure the API implementation in the src *.cs file is documented with triple slash comments, so the PR reviewers can sign off that change.

[MihaZupan]

The SslStream part of this logic is currently unreachable - tracked by #19752

runtime/src/libraries/System.Net.HttpListener/src/System/Net/Managed/HttpEndPointListener.cs

Lines 56 to 60 in d7ae8c6

	if (secure)
	{
	_secure = secure;
	_cert = HttpListener.LoadCertificateAndKey(addr, port);
	}

runtime/src/libraries/System.Net.HttpListener/src/System/Net/Managed/HttpListener.Certificates.cs

Lines 20 to 24 in d7ae8c6

	internal static X509Certificate? LoadCertificateAndKey(IPAddress addr, int port)
	{
	// TODO https://github.com/dotnet/runtime/issues/19752: Implement functionality to read SSL certificate.
	return null;
	}

runtime/src/libraries/System.Net.HttpListener/src/System/Net/Managed/HttpEndPointListener.cs

Lines 115 to 119 in d7ae8c6

	if (_secure && _cert == null)
	{
	accepted.Close();
	return;
	}

[stephentoub]

Why haven't we explicitly marked it?

[MihaZupan]

I believe it was to reduce the noise for anyone still using it without suppressing it at the project level.
They must suppress the warning at least once when creating the request, but not everywhere else they might have plumbed the types through.

[ManickaP]

🎉