Worked on the firebase/firebase-android-sdk repository to enhance the security and robustness of Android messaging data by addressing a bug related to the RemoteMessage.getData() method. Applied backend development skills in Java to implement a defensive copy pattern, ensuring that getData() returns a new HashMap containing the original data. This approach prevents external code from mutating the internal state, thereby improving data integrity and aligning with security best practices. The change was linked to a tracked bug and related issue, reflecting a focus on maintaining safer public APIs. The work demonstrates attention to secure coding and backend reliability in Java environments.