As per the top two answers in: maven dependencies groovy. I\'m trying to compile a mixed Java 6 + Groovy project with Maven, using the GMaven-plugin from org.codehaus.gmaven
I had the same problem. I was missing the providerSelection configuration setting for 1.7.
Try this configuration and it should work for you.
org.codehaus.gmaven
gmaven-plugin
1.2
1.7
org.codehaus.gmaven.runtime
gmaven-runtime-1.7
1.2
org.codehaus.groovy
groovy-all
org.codehaus.groovy
groovy-all
1.7.0
generateStubs
compile
generateTestStubs
testCompile