Worked on reliability improvements across the spring-security and spring-ai repositories, focusing on backend development with Java and Elasticsearch. Addressed a potential NullPointerException in AuthoritiesAuthorizationManager by implementing null-safe handling for granted authority strings, ensuring the authorization flow remains robust even when authorities are missing. Added a regression test to validate this behavior and prevent future issues. In spring-ai, resolved issues with Elasticsearch query generation by correcting the quoting and grouping of IN and NIN expressions, which improved the accuracy and reliability of search features. Emphasized unit testing and careful code review to reduce runtime errors and support incidents.