The JPA Derived Queries in this scenario, in this article and codebase are built upon distinct queries that align with the GraphQL endpoint.

These endpoints are not stitched, federated or composed in any way other than their 1:1 schema query to SQL query through the Java Spring Boot database repository interface.

If you are looking to solve a scenario in which stitching is required, it appears that there are many libraries for supporting proper implementation.

The best way about this is most likely creating an internal Component fabric to compose responses from multiple endpoints asynchronusly into a composite POJO Class.