OnBeforeTokenRequest is no longer experimental (#4603)

* OnBeforeTokenRequest is longer experimental

* OnBeforeTokenRequest is longer experimental

* fix

* fix

Author: bgavrilMS

src/client/Microsoft.Identity.Client/Extensibility/AbstractConfidentialClientAcquireTokenParameterBuilderExtension.cs

@@ -24,8 +24,7 @@ public static AbstractAcquireTokenParameterBuilder<T> OnBeforeTokenRequest<T>(
             this AbstractAcquireTokenParameterBuilder<T> builder, 
             Func<OnBeforeTokenRequestData, Task> onBeforeTokenRequestHandler) 
             where T : AbstractAcquireTokenParameterBuilder<T>
-        {
-            builder.ValidateUseOfExperimentalFeature();
+        {            
             builder.CommonParameters.OnBeforeTokenRequestHandler = onBeforeTokenRequestHandler;
 
             return builder;

tests/Microsoft.Identity.Test.Integration.netfx/HeadlessTests/ClientCredentialsTests.cs

@@ -150,7 +150,6 @@ public async Task WithOnBeforeTokenRequest_TestAsync(Cloud cloud, TargetFramewor
             IConfidentialClientApplication confidentialApp = ConfidentialClientApplicationBuilder
                 .Create(settings.ClientId)
                 .WithAuthority(settings.Authority, true)
-                .WithExperimentalFeatures(true)
                 .WithTestLogging()
                 .Build();