We automatically test REST API based on their specifications, particularly OpenAPI ones. To our surprise, many of our tests failed, meaning that the OpenAPI definition and the actual API were not an exact match.
g9 is one of the most flexible code-generator tools I’ve seen. It generates both the front-end, the back-end and the database for you. And it’s fully integrated in Eclipse
Details of our UML Profile to model OData Web APIs. Once you have your UML model annotated with OData stereotypes you could automate the generation of your OData definition files.