Kadin Rabo developed a flexible type variation handling feature for the substrait-io/substrait-java repository, focusing on enhancing the UserDefined type to support multiple physical representations or semantics for a single logical type. By introducing the typeVariationReference parameter, Kadin enabled improved interoperability and customization for Java-based Substrait consumers. The work involved updating the core API and data model in Java, ensuring backward compatibility while laying the foundation for downstream efficiency. Kadin’s approach included preparing documentation and review materials to facilitate upgrade paths and adoption. This engineering effort demonstrated depth in API development and software design, addressing extensibility and maintainability concerns.