remove @override for interface methods as source compatibility is 1.5

pom.xml has javac compiler level set to 1.5 and that does not support
@override for interface methods. Build would fail if somebody actually
ran it with a 1.5 java compiler. See
http://stackoverflow.com/questions/1193184/does-maven-really-honor-the-source-tag-in-the-compiler-plugin
why this built before even though it should have failed.