I recently made some simple updates to Wish by using Java 1.5 generics and autoboxing/unboxing. Making Java source changes was the easy part, while the time consuming part was on hunting for information on Maven-related changes.
I started by changing maven-compiler-plugin source and target in pom.xml:
Caused by: net.sourceforge.pmd.ast.ParseException: Can't use generics unless running in JDK 1.5 mode!
which led me to change maven-pmd-plugin targetJdk:
If you don’t already have any existing checkstyle rules, create checkstyle.xml file and place it on the root directory of the project (i.e. same place as pom.xml) and add configLocation to maven-checkstyle-plugin: