I am using Adobe Cloud CI/CD build pipeline for my build process which is integrated with Sonar Qube.
As a code Model, I have a very simple POJO, with 3 attributes, @inject annotation for each one, and getters and setters as usual.
When I push the code to remote/develop the SonarQube starts to test the code, then I can see the code coverage is under 50% all the time as shown in the below image.
You have to write Junit test cases to increase code coverage for your model. Make sure your test cases cover maximum code.