Improve AAD token acquisition error handling

[Divang Sharma (divang)]

Description

Improves error handling for AAD token acquisition through Managed Identity and DefaultAzureCredential.

Token acquisition previously surfaced timeout and interruption failures as generic Managed Identity token acquisition errors. This change introduces explicit handling for these cases while preserving the underlying exception cause for diagnostics.

Related to #3038

Changes

• Centralize credential token conversion and error handling for:
  • ManagedIdentityCredential
  • DefaultAzureCredential
• Report token-acquisition timeouts with a dedicated error message.
• Report interrupted token acquisition with a dedicated error message.
• Restore the thread interrupt flag when token acquisition is interrupted.
• Preserve the original credential failure as the SQLServerException cause.
• Preserve the credential-cache eviction behavior introduced for transient failures.
• Continue using the existing error when credential acquisition completes without returning a token.
• Add focused unit tests for:
  • Successful token conversion
  • Credential failure propagation
  • Token-acquisition timeout
  • Empty token response
  • Thread interruption and interrupt-flag restoration
• Update the existing Managed Identity timeout test to verify the timeout-specific error.

Testing

mvn -Pjre25 "-Dtest=SQLServerSecurityUtilityTest,SQLServerConnectionUnitTest" test

[codecov]

Codecov Report

❌ Patch coverage is 86.53846% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 61.68%. Comparing base (644188c) to head (5908a5b).
⚠️ Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
...microsoft/sqlserver/jdbc/SQLServerMSAL4JUtils.java	75.00%	7 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #3061      +/-   ##
============================================
+ Coverage     60.84%   61.68%   +0.84%     
- Complexity     5287     5347      +60     
============================================
  Files           154      154              
  Lines         36734    36872     +138     
  Branches       6742     6796      +54     
============================================
+ Hits          22351    22745     +394     
+ Misses        10598    10270     -328     
- Partials       3785     3857      +72     

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[Copilot]

Copilot review overview

🟢 Approval recommended

The focused implementation preserves existing behavior while adding correctly tested diagnostics.

Review effort: Balanced
Findings: None

What changed in this PR

Improves AAD credential failure diagnostics while preserving credential-cache eviction behavior.

Changes:

• Adds timeout- and interruption-specific error mapping.
• Restores interrupt status and preserves underlying causes.
• Adds focused tests and updates timeout assertions.

File	Description
SQLServerSecurityUtility.java	Centralizes token exception mapping and conversion.
SQLServerResource.java	Adds timeout and interruption messages.
SQLServerSecurityUtilityTest.java	Tests exception mapping and interrupt restoration.
SQLServerConnectionUnitTest.java	Verifies timeout-specific behavior.

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[Copilot]

Copilot review overview

🟡 Changes recommended

Exception formatting can mask failures, and nested worker interruptions incorrectly interrupt the caller thread.

Review effort: Balanced
Findings: 2

Open (2)

• Avoid restoring interruption from nested ExecutionException causes · New
• Prevent exception messages from breaking MessageFormat formatting · New

[Copilot]

Copilot review overview

🟡 Changes recommended

Three existing timeout tests still expect the replaced R_connectionTimedOut message.

Review effort: Balanced
Findings: 1

Open (1)

• Update stale timeout test assertions · New

Resolved since last review (2)

• Prevent exception messages from breaking MessageFormat formatting
• Avoid restoring interruption from nested ExecutionException causes

[Copilot]

Copilot review overview

🔵 Needs a closer look

Worker-thread interruptions can incorrectly set the login thread’s interrupt flag.

Review effort: Balanced
Findings: 1

Open (1)

• Update stale timeout test assertions

Previously missed (1)

In code that hasn't changed since last review

Avoid restoring caller interrupt flag for worker-thread interruptions

src/​main/​java/​com/​microsoft/​sqlserver/​jdbc/​SQLServerSecurityUtility.java:500

Only restore the interrupt flag when the current login thread was interrupted. This scans an arbitrary asynchronous credential failure and always interrupts the caller, so an InterruptedException raised by an Azure Identity/Reactor worker will spuriously leave the unrelated login thread interrupted. The MSAL mapper in this PR already avoids this for ExecutionException-wrapped worker interruptions; this path needs the same distinction (for example, identify Reactor's blockOptional interruption wrapper/marker rather than treating every nested interruption as caller interruption).

[Copilot]

Copilot review overview

🟢 Approval recommended

The behavior is well tested, with only minor formatter cleanup requested.

Review effort: Balanced
Findings: 1

Open (1)

• Wrap assertion message to comply with 120-column limit · New

Resolved since last review (1)

• Update stale timeout test assertions

[Copilot]

Copilot review overview

🔵 Needs a closer look

Worker-side interruptions can incorrectly mark the calling login thread as interrupted.

Review effort: Balanced
Findings: None

Resolved since last review (1)

• Wrap assertion message to comply with 120-column limit

Previously missed (1)

In code that hasn't changed since last review

Distinguish caller interruption from worker-propagated interruption

src/​main/​java/​com/​microsoft/​sqlserver/​jdbc/​SQLServerSecurityUtility.java:499

This unconditionally interrupts the login thread whenever any nested cause is an InterruptedException. Unlike the direct Future.get path below, this reactive chain may also deliver an interruption raised on an Azure/Reactor worker; in that case the caller was never interrupted, but it is returned to the pool with its interrupt flag set. The MSAL mapper explicitly distinguishes direct caller interruption from an ExecutionException carrying worker interruption (and tests that distinction). Please likewise distinguish an interruption produced by this thread's blockOptional() wait from one propagated by the credential pipeline before restoring the caller flag.