[MDEP-453] Change Maven prerequisite to 2.2.1

git-svn-id: https://svn.apache.org/repos/asf/maven/plugins/trunk@1616850 13f79535-47bb-0310-9956-ffa450edef68
remove unused imports

git-svn-id: https://svn.apache.org/repos/asf/maven/plugins/trunk@1616857 13f79535-47bb-0310-9956-ffa450edef68
- Improved code.

git-svn-id: https://svn.apache.org/repos/asf/maven/plugins/trunk@1616862 13f79535-47bb-0310-9956-ffa450edef68