---

This section details on the original issue you should resolve

<issue_title>Deprecate legacy ManagedIdentityCredential ctors</issue_title>
<issue_description>## Background

As ManagedIdentityCredential's API surfaced has evolved, the following 2 ctors are no longer recommended:

azure-sdk-for-net/sdk/identity/Azure.Identity/src/Credentials/ManagedIdentityCredential.cs

Lines 46 to 66 in 90a3d59

	[EditorBrowsable(EditorBrowsableState.Never)]
	public ManagedIdentityCredential(string clientId = null, TokenCredentialOptions options = null)
	: this(new ManagedIdentityClient(new ManagedIdentityClientOptions { ManagedIdentityId = string.IsNullOrEmpty(clientId) ? ManagedIdentityId.SystemAssigned : ManagedIdentityId.FromUserAssignedClientId(clientId), Pipeline = CredentialPipeline.GetInstance(options, IsManagedIdentityCredential: true), Options = options }))
	{
	_logAccountDetails = options?.Diagnostics?.IsAccountIdentifierLoggingEnabled ?? false;
	}
	/// <summary>
	/// Creates an instance of <see cref="ManagedIdentityCredential"/> capable of authenticating a resource with a user-assigned managed identity.
	/// </summary>
	/// <param name="resourceId">
	/// The resource ID to authenticate for a <see href="https://learn.microsoft.com/entra/identity/managed-identities-azure-resources/overview#how-a-user-assigned-managed-identity-works-with-an-azure-vm">user-assigned managed identity</see>.
	/// </param>
	/// <param name="options">Options to configure the management of the requests sent to Microsoft Entra ID.</param>
	[EditorBrowsable(EditorBrowsableState.Never)]
	public ManagedIdentityCredential(ResourceIdentifier resourceId, TokenCredentialOptions options = null)
	: this(new ManagedIdentityClient(new ManagedIdentityClientOptions { ManagedIdentityId = ManagedIdentityId.FromUserAssignedResourceId(resourceId), Pipeline = CredentialPipeline.GetInstance(options, IsManagedIdentityCredential: true), Options = options }))
	{
	_logAccountDetails = options?.Diagnostics?.IsAccountIdentifierLoggingEnabled ?? false;
	_clientId = resourceId.ToString();
	}

From a behavioral perspective, the following ctors are equivalent:

ManagedIdentityCredential credential1 = new();
ManagedIdentityCredential credential2 = new(ManagedIdentityId.SystemAssigned);

ManagedIdentityCredential credential1 = new("<client_id>");
ManagedIdentityCredential credential2 = new(ManagedIdentityId.FromUserAssignedClientId("<client-id>"));

The same is true for the following 2 ctors:

ManagedIdentityCredential credential1 = new(new ResourceIdentifier("<resource_id>"));
ManagedIdentityCredential credential2 = new(
    ManagedIdentityId.FromUserAssignedResourceId(new ResourceIdentifier("<resource_id>")));

The newer ctors make the intent clear; that is, whether system-assigned or user-assigned managed identity is to be used. Furthermore, the older ctors are already suppressed from display in IntelliSense and Learn API ref docs (thanks to [EditorBrowsable(EditorBrowsableState.Never)].

Proposal

Discourage further use of the 2 older ctors by deprecating them. To accomplish this, apply the following [Obsolete()] attribute to each of them:

[Obsolete("Use constructor ManagedIdentityCredential(ManagedIdentityId id, TokenCredentialOptions options = null) or ManagedIdentityCredential(ManagedIdentityCredentialOptions options).")]

The result is fewer ways to accomplish the same thing and a much clearer intent.

Finally, add a CHANGELOG entry to raise awareness of the deprecated ctors.</issue_description>

Comments on the Issue (you are @copilot in this section)

@scottaddie Heads up there will be minor changes required in Microsoft.Extensions.Azure too. Affected files include:

• ClientFactory.cs
• AzureClientFactoryTests.cs</comment_new>