How to use
Just add the following parent declaration in your project parent POM :
How to upgrade
Just change the version of the parent pom you used previously. Have a look at each release note of each version you upgrade to see if there are some notable changes which require to modify something in your project.
How to configure
The parent defines and uses a set of cutom properties that can be reused and/or overrided by projects to customize the default behavior of maven defined in the parent pom.
To work Sonar requires Java 1.5 or later. So, your plugin should work under Java 1.5. However if you really want to have Java 1.6 as target platform, then you can use following configuration :