Cannot build eclipse-integration-gradle project due to missing m2e classes

Follow the installation instructions of the README file, using Eclipse JEE 4.2. Everything works fine except that there is a compile error in M2EUtils since it cannot find the following classes (packages):

import org.eclipse.m2e.core.internal.MavenPluginActivator;
import org.eclipse.m2e.core.internal.project.registry.MavenProjectManager; import org.eclipse.m2e.core.project.IMavenProjectFacade;

I fixed it by installing 'Groovy-Eclipse-M2E Integration' (contrary to what it says in the docs to exclude it).

Either the docs are not correct/uptodate or my solution is just a hack and there is a correct solution I do not know of.