Change session observer list type

[breedx-splk]

Resolves #1877

[Copilot]

Pull request overview

Updates SessionManager’s internal observer storage to address concurrent modification risk described in #1877 (iteration safety when observers are mutated during callbacks), aligning the implementation with a concurrency-safe list type for observer notification.

Changes:

• Replace Collections.synchronizedList with CopyOnWriteArrayList for SessionManager observers.
• Add a new unit test intended to cover adding an observer while notifications are in progress.

PR Merge Tier: Tier 2 (small internal concurrency/robustness fix + test)

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
android-agent/src/main/kotlin/io/opentelemetry/android/agent/session/SessionManager.kt	Switch observer list implementation to CopyOnWriteArrayList to make iteration safe under concurrent mutation.
android-agent/src/test/kotlin/io/opentelemetry/android/agent/session/SessionManagerTest.kt	Add coverage for observer addition during notification (currently asserts behavior that doesn’t match implementation).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.33%. Comparing base (c875da2) to head (b272c95).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1902   +/-   ##
=======================================
  Coverage   65.33%   65.33%           
=======================================
  Files         169      169           
  Lines        3871     3871           
  Branches      420      420           
=======================================
  Hits         2529     2529           
  Misses       1211     1211           
  Partials      131      131           

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[fractalwrench]

There's a CI failure where the new test case is failing. Otherwise this looks good

[aranhave]

LGTM!