Denys Khomenko worked on the Backbase/stream-services repository, focusing on improving product catalog integrity by addressing a critical data mapping issue. He implemented a fix in Java to ensure that external_parent_id is correctly mapped to parent_id within the ProductMapper, resolving inconsistencies in product hierarchy handling. To validate this change, Denys updated the associated unit tests, enhancing test coverage for parent-child product relationships and reducing the risk of future regressions. His work demonstrated proficiency in mapper development and unit testing, contributing to more reliable downstream analytics and aligning with ongoing maintenance efforts. The scope was targeted and technically thorough.