add OS default broker auth to DAC

[g2vinay]

No description provided.

[Copilot]

Pull Request Overview

This PR adds OS Broker authentication support to the DefaultAzureCredential by introducing a new OSBrokerCredential, integrating it into the credential chains, and updating tests and documentation.

• Introduce OSBrokerCredential and refactor IdentityUtil for broker availability.
• Integrate OSBrokerCredential into both developer-only and default credential chains in DefaultAzureCredentialBuilder.
• Update existing tests to mock and assert OS broker behavior; add a new test for broker-unavailable scenarios and document troubleshooting steps.

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
sdk/identity/azure-identity/src/test/java/com/azure/identity/DefaultAzureCredentialTest.java	Added OSBrokerCredential mocks and assertions to user and developer credential chain tests.
sdk/identity/azure-identity/src/test/java/com/azure/identity/DacOsBrokerCredentialTest.java	Added new test covering the broker-unavailable error path for OSBrokerCredential.
sdk/identity/azure-identity/src/main/java/com/azure/identity/implementation/util/IdentityUtil.java	Refactored broker availability check; added isVsCodeBrokerAuthAvailable and simplified isBrokerAvailable.
sdk/identity/azure-identity/src/main/java/com/azure/identity/OSBrokerCredential.java	Introduced the OSBrokerCredential implementation, handling dynamic broker credential creation.
sdk/identity/azure-identity/src/main/java/com/azure/identity/DefaultAzureCredentialBuilder.java	Integrated OSBrokerCredential into the developer credentials list.
sdk/identity/azure-identity/TROUBLESHOOTING.md	Documented broker-authentication errors, mitigation steps, and Windows-only support note.

Comments suppressed due to low confidence (4)

sdk/identity/azure-identity/src/main/java/com/azure/identity/implementation/util/IdentityUtil.java:182

• [nitpick] Update this comment to reflect that the method also verifies broker availability (i.e., it returns true only if the broker is available and the VS Code auth record file exists).

        // Check if VS Code broker auth record file exists

sdk/identity/azure-identity/src/main/java/com/azure/identity/OSBrokerCredential.java:16

• Add JavaDoc to describe the purpose and behavior of OSBrokerCredential and its getToken method, in line with Azure SDK public API documentation requirements.

class OSBrokerCredential implements TokenCredential {

sdk/identity/azure-identity/src/main/java/com/azure/identity/OSBrokerCredential.java:57

• [nitpick] Capitalize the beginning of this error message (e.g., "Azure-identity-broker dependency is not available...") to match sentence casing conventions used elsewhere.

                new CredentialUnavailableException("azure-identity-broker dependency is not available. "

sdk/identity/azure-identity/src/test/java/com/azure/identity/DacOsBrokerCredentialTest.java:10

• Add a test for the successful (happy-path) scenario where the broker dependency is available and getToken returns a valid AccessToken.

public class DacOsBrokerCredentialTest {

[christothes]

LGTM

[g2vinay]

/check-enforcer override