Initial port to System.Text.Json.

[azchohfi]

Fixes #3407

Changes proposed in this request
Removes Newtonsoft.Json, and replaces it with System.Text.Json

Testing
All Unit Tests are passing, but there is more work to be done since this is still not using source generators, so trimming would still affect it.

Performance impact
Performance should greatly improve after the source generators are implemented since no reflection will be used anymore for the Json parsing.

[bgavrilMS]

nit: this class can be hard deprecated if needed.

[pmaytak]

It's already obsoleted. Can't delete it since it affects public API.

microsoft-authentication-library-for-dotnet/src/client/Microsoft.Identity.Client/AppConfig/TraceTelemetryConfig.cs

Lines 18 to 20 in b9faf12

	[Obsolete("Telemetry is sent automatically by MSAL.NET. See https://aka.ms/msal-net-telemetry.", false)]
	[EditorBrowsable(EditorBrowsableState.Never)]
	public class TraceTelemetryConfig : ITelemetryConfig

[azchohfi]

@pmaytak/@bgavrilMS I've just pushed the changes that added the source generated Json parsing.

[azchohfi]

There are still some IL trimming warnings, so this can't be merged as-is yet. Still investigating, but it is probably something that is being generated for a property that shouldn't be.

[pmaytak]

Thanks @azchohfi. I'll take a deeper look, but initial thoughts:

• If I remember correctly, some defaults are different for Newtonsoft and System.Text.Json, like case-sensitive vs case-insensitive, need to make sure the behavior is the same. Need to verify if our JSON tests are sufficient.
• Thinking it might be good to aggregate all JSON related code into one class, like JsonHelper. (Although this will be fine to do in a separate PR).
• We do have some perf tests that we can run for before/after.

[azchohfi]

We should also consider adding a .Net6 target for other platforms, such as Linux/MacOS, so we support trimming for them too. The way the project is structured, we only target net5.0-windows10.0.17763.0, so a Linux project would probably not benefit completely from this.

[azchohfi]

As well as a test app with trimming enabled to make sure things are properly trimmed.

[azchohfi]

We should also consider adding a .Net6 target for other platforms, such as Linux/MacOS, so we support trimming for them too. The way the project is structured, we only target net5.0-windows10.0.17763.0, so a Linux project would probably not benefit completely from this.

Yeah, this is a must. If we don't, then a simple net6.0 project will reference the netcore app 3.1 TFM, which will have trimming issues since its methods can't be annotated properly.

[azchohfi]

@Sergio0694 is it possible to still annotate the one method that is complaining about dynamic access on netcoreapp3.1?
It is a simple call to System.Activator.CreateInstance(Type,Object[]), which is mostly only used by the tests, but it is a public method and I don't want to remove a public API with this PR. We could re-implement it with a switch statement since we are talking about 4 possible types that are created here, but I wonder in general if we have a better answer.

[azchohfi]

Btw, this is the call:

microsoft-authentication-library-for-dotnet/src/client/Microsoft.Identity.Client/MsalException.cs

Line 192 in fe6c9ab

MsalException ex = Activator.CreateInstance(exceptionType, errorCode, errorMessage) as MsalException;

[azchohfi]

Ok, it is definitely working \o/ got all the issues working with this last commit.

[azchohfi]

I'll send another PR from a branch of this repo, not from my fork, so it will run the build properly.

[azchohfi]

Closed in favor of #3435