Worked on the googleapis/google-cloud-rust repository to deliver a targeted bug fix for Workload Identity Federation, focusing on improving the reliability and security of Google Cloud credentials integration. Addressed issues in impersonation configuration parsing by refining how service account impersonation settings are handled, and enhanced credential deserialization to support optional fields in subject token formats. Developed and added comprehensive tests to validate Kubernetes Workload Identity Federation configurations for both direct identity and impersonation scenarios. Utilized Rust for robust JSON parsing and API integration, ensuring the credentials module is more stable and reducing the risk of misconfiguration in production environments.