Niels L. enhanced the Backbase/stream-services repository by extending the OpenAPI stream-legal-entity API with new data group types, including CASE_DEFINITION and PROCESS_INSTANCE, to support richer data governance. He updated the openapi.yaml and changelog files using YAML and Markdown, ensuring the API surface accurately reflected these additions after a previous revert. Niels also refreshed the compatibility matrix in the README to align with newer Stream and Banking Services versions, clarifying integration requirements for Java and Spring Boot environments. His work focused on API design, development, and documentation, improving release readiness and reducing integration risk through up-to-date specifications.