The default settings of jacoco and sonar show coverage only from tests within the same maven submodule. But in some cases one has test code that is not in the same module as the code being tested, eg in integration tests. It would be great to have all the coverage reports aggregated into a single coverage. This project is an example of how to do this. It is an implementation (actually almost a copy) of https://stackoverflow.com/a/15535970/3312952.
The idea is to create a single jacoco.exec report by appending to it in every submodule.
This is simpler than using the jacoco:report-aggregate goal.