Propagate onboarding telemetry blob through broker success and failure paths, Fixes AB#3462876

[wzhipan]

Makes MsalBrokerResultAdapter carry the onboarding telemetry blob symmetrically across every broker outcome (success, failure, cancel), closing the failure-path gap Veena flagged on #3111 and unblocking the broker recorder-lifecycle work.

What this adds:

Failure path (was the original A3 scope)

1. BaseException.onboardingBlob field with getter/setter (common4j).
2. MsalBrokerResultAdapter.bundleFromBaseException now serializes exception.onboardingBlob into the result bundle (symmetric with the existing ClientDataInfo serialization right above it).
3. MsalBrokerResultAdapter.getBaseExceptionFromBundle extracts the blob from the deserialized BrokerResult and attaches it to the reconstructed exception via setOnboardingBlob.

Success path (added in second commit)

4. MSAL-only overloads on MsalBrokerResultAdapter:

   • bundleFromAuthenticationResult(result, onboardingBlob, version)
   • buildBrokerResultFromAuthenticationResult(result, onboardingBlob, version)

   The broker calls these from AccountChooserActivity.returnSuccessToCallingActivity (upcoming PR) to ship the finalized recorder blob to the client. Existing overloads are preserved and delegate to the new ones with null, so no behavior change for existing callers (including AdalBrokerResultAdapter which doesn't need this).

After this, OneAuth / Common can emit onboarding telemetry on the brokered success, failure, and cancel outcomes via:

• acquireTokenResult.getOnboardingBlob() (success — already wired in Broker IPC plumbing for onboarding telemetry blob, Fixes AB#3568357 #3111)
• exception.getOnboardingBlob() (failure/cancel — new)

Why now: Required by upcoming broker recorder-lifecycle work in PR #163 follow-ups, which writes the recorder blob on every termination path.

Tests: MsalBrokerResultAdapterTests adds 4 new round-trip tests (2 failure-path, 2 success-path). All 6 testOnboardingBlob_* tests pass locally:
./gradlew :common:testLocalDebugUnitTest --tests *MsalBrokerResultAdapterTests*testOnboardingBlob*

Safety: Telemetry-only; never affects auth logic. No flight gate (blob is only present if a prior PR seeded it).

Fixes AB#3462876

[github-actions]

✅ Work item link check complete. Description contains link AB#3462876 to an Azure Boards work item.

[Copilot]

Pull request overview

This PR extends the onboarding telemetry feature so the broker-populated onboarding blob is preserved not only on success (AcquireTokenResult) but also when brokered flows fail/cancel by carrying the blob on BaseException and round-tripping it through the broker result bundle.

Changes:

• Add BaseException.onboardingBlob (nullable) with accessor methods to carry the serialized onboarding telemetry blob on failure paths.
• Update MsalBrokerResultAdapter to serialize exception.onboardingBlob into BrokerResult and restore it back onto the reconstructed BaseException.
• Add unit tests validating blob round-trip behavior and null behavior parity; update changelog.txt with a MINOR entry.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
common4j/src/main/com/microsoft/identity/common/java/exception/BaseException.java	Adds onboardingBlob field + getter/setter to carry onboarding telemetry through exception-based failure paths.
common/src/main/java/com/microsoft/identity/common/internal/result/MsalBrokerResultAdapter.java	Serializes/deserializes onboarding blob for exceptions via BrokerResult to preserve it across IPC on failure/cancel outcomes.
common/src/test/java/com/microsoft/identity/common/internal/request/MsalBrokerResultAdapterTests.kt	Adds tests ensuring onboarding blob round-trips through exception→bundle→exception and stays null when unset.
changelog.txt	Records the change as a MINOR feature addition for vNext.

[github-actions]

✅ Work item link check complete. Description contains link AB#3462876 to an Azure Boards work item.

[Prvnkmr337]

Overall change LGTM, ensure the build and tests are passing. Ensure on oneAuth side when reading blob check for Null or empty condition before operating on it.

[wzhipan]

Rebased onto latest dev and resolved changelog conflicts. Please re-review when you get a chance.

[Prvnkmr337]

Please check the coverage check failure, seems like false positive.