Revert "Groovy 2.6.+"
Revert "Groovy 2.6.+"

This reverts commit 4fc69fa147a02c6ba77fe9852ef0899b2f179c29.

cloudfoundry-community/jboss-buildpack,rakutentech/java-buildpack,rakutentech/java-buildpack,cloudfoundry/java-buildpack,cloudfoundry/java-buildpack,cloudfoundry-community/tomee-buildpack,cloudfoundry-community/jboss-buildpack,cloudfoundry-community/tomee-buildpack,Appdynamics/java-buildpack,Appdynamics/java-buildpack