Redesign the Managed Identity public API

[neha-bhargava]

Add an application level API for managed identity:

var mi = ManagedIdentityApplicationBuilder  // This class will also have token cache behavior
  .Create() // Or .Create("user-assigned-managed-identity-guid")
  .Build();

AuthenticationResult result = await mi.AcquireTokenForManagedIdentity(scopes)  // This is the only method of this new class
  .ExecuteAsync().ConfigureAwait(false);

Ref: https://identitydivision.visualstudio.com/DevEx/_git/AuthLibrariesApiReview/pullrequest/7003?_a=files&path=/ManagedIdentity/ManagedIdentity.md

[pmaytak]

Will this from the spec be implemented? I guess not?

When using a normal confidential client federated by Managed Identity, there are several sub-options here.

var cca = ConfidentialClientApplicationBuilder()
  .Create(clientId)  // The normal CCA's client id
  .WithManagedIdentity()  // Or .WithManagedIdentity("user-assigned-managed-identity-guid")
  ...  // Other modifiers needed by a normal CCA, such as WithAuthority(...)
  .Build();
var result1 = await cca.AcquireTokenForClient("https://graph.microsoft.com/.default")  // Same as a normal CCA
  .ExecuteAsync().ConfigureAwait(false);  // It will create and call ManagedIdentityApplication object internally