Whole step by step description from my blog series can be found here

• Building an OData Service with a Spring Java Application using Olingo – Part I
• Building an OData Service with a Spring Java Application using Olingo – Part II
• Building an OData Service with a Spring-Boot Java Application using Olingo – Part III (Payloads and Custom Logic)

What you find here is a working example of an olingo spring application.

You can run this app locally by executing the command 'mvn spring-boot:run' in the terminal of the project folder.

Using Postman you can then call the URL localhost:8080/odata/$metadata to fetch the metadata:

The entity relation model I use for the example is a simple one:

It's important that you send the payload in the correct format:

if you then call the Mothers(1) entity, you'll also get a positive result back: