Developed a robust AnyOf Validator for Required Fields in the americanexpress/synapse repository, focusing on backend development and validation using Java. The solution introduced a custom annotation and validator implementation that enforces at least one non-empty, non-blank field across multi-field objects, reducing risks related to incomplete payloads and improving data integrity. Comprehensive unit tests were written to ensure reliability and maintainability, while a targeted test fix addressed an invalid scenario to stabilize the test suite and enhance CI confidence. This work demonstrated a methodical approach to validation design, leveraging annotation-driven patterns and thorough testing to support scalable backend systems.