Get code coverage for Java project with Cobertura. The plugin is based on the cobertura-maven-plugin and so can only be used to compute code coverage information on Maven projects.
Sonar Cobertura Plugin
See Code Coverage by Unit Tests for Java Project tutorial.
In case the cobertura-maven-plugin is defined in the pom.xml of your project, Sonar will use the version defined in the pom and can potentially not function properly.