Obsolete AuthenticationManager (#866)

Author: HaoK

src/Microsoft.AspNetCore.Http.Abstractions/Authentication/AuthenticationManager.cs

@@ -9,6 +9,7 @@
 
 namespace Microsoft.AspNetCore.Http.Authentication
 {
+ [Obsolete("This is obsolete and will be removed in a future version. See https://go.microsoft.com/fwlink/?linkid=845470.")]
  public abstract class AuthenticationManager
  {
  /// <summary>

src/Microsoft.AspNetCore.Http/Authentication/DefaultAuthenticationManager.cs

@@ -11,6 +11,7 @@
 
 namespace Microsoft.AspNetCore.Http.Authentication.Internal
 {
+ [Obsolete("This is obsolete and will be removed in a future version. See https://go.microsoft.com/fwlink/?linkid=845470.")]
  public class DefaultAuthenticationManager : AuthenticationManager
  {
  // Lambda hoisted to static readonly field to improve inlining https://github.com/dotnet/roslyn/issues/13624

src/Microsoft.AspNetCore.Http/DefaultHttpContext.cs

@@ -28,7 +28,11 @@ public class DefaultHttpContext : HttpContext
 
  private HttpRequest _request;
  private HttpResponse _response;
+
+#pragma warning disable CS0618 // Type or member is obsolete
  private AuthenticationManager _authenticationManager;
+#pragma warning restore CS0618 // Type or member is obsolete
+
  private ConnectionInfo _connection;
  private WebSocketManager _websockets;
 
@@ -66,7 +70,9 @@ public virtual void Uninitialize()
  }
  if (_authenticationManager != null)
  {
+#pragma warning disable CS0618 // Type or member is obsolete
  UninitializeAuthenticationManager(_authenticationManager);
+#pragma warning restore CS0618 // Type or member is obsolete
  _authenticationManager = null;
  }
  if (_connection != null)
@@ -196,7 +202,9 @@ protected virtual void UninitializeHttpResponse(HttpResponse instance) { }
  protected virtual ConnectionInfo InitializeConnectionInfo() => new DefaultConnectionInfo(Features);
  protected virtual void UninitializeConnectionInfo(ConnectionInfo instance) { }
 
+ [Obsolete("This is obsolete and will be removed in a future version. See https://go.microsoft.com/fwlink/?linkid=845470.")]
  protected virtual AuthenticationManager InitializeAuthenticationManager() => new DefaultAuthenticationManager(this);
+ [Obsolete("This is obsolete and will be removed in a future version. See https://go.microsoft.com/fwlink/?linkid=845470.")]
  protected virtual void UninitializeAuthenticationManager(AuthenticationManager instance) { }
 
  protected virtual WebSocketManager InitializeWebSocketManager() => new DefaultWebSocketManager(Features);