Worked on stabilizing the test infrastructure for the spring-projects/spring-integration repository by addressing a concurrency issue in the test execution process. Focused on resolving a ConcurrentModificationException in SpringIntegrationTestExecutionListener, the solution involved making the autoStartupCandidates list in MockIntegrationContext unmodifiable. This change, implemented using Java and Spring Integration, improved the reliability of parallel test execution and reduced flakiness in continuous integration pipelines. By enhancing the immutability of test components, the work contributed to safer and more predictable release cycles. The approach demonstrated attention to robust testing practices and a clear understanding of concurrency challenges in Java-based test environments.