plugins/maven/src/main/resources/META-INF/groovy-support.xml

<idea-plugin url="http://www.jetbrains.com/idea">
  <extensions defaultExtensionNs="org.jetbrains.idea.maven">
    <importer implementation="org.jetbrains.idea.maven.plugins.groovy.Groovy_1_0_Importer"/>
    <importer implementation="org.jetbrains.idea.maven.plugins.groovy.Groovy_1_1_plus_Importer"/>
    <importer implementation="org.jetbrains.idea.maven.plugins.groovy.GroovyGmavenImporter"/>
    <importer implementation="org.jetbrains.idea.maven.plugins.groovy.GroovyEclipseCompilerImporter"/>

    <pluginDescriptor mavenId="org.codehaus.groovy.maven:gmaven-plugin">
      <param name="source" languageProvider="org.jetbrains.idea.maven.plugins.groovy.MavenGroovyLanguageProvider"/>
    </pluginDescriptor>

    <pluginDescriptor mavenId="org.codehaus.gmaven:gmaven-plugin">
      <param name="source" languageProvider="org.jetbrains.idea.maven.plugins.groovy.MavenGroovyLanguageProvider"/>
    </pluginDescriptor>

    <pluginDescriptor mavenId="org.codehaus.gmaven:groovy-maven-plugin">
      <param name="source" languageProvider="org.jetbrains.idea.maven.plugins.groovy.MavenGroovyLanguageProvider"/>
    </pluginDescriptor>
  </extensions>

  <extensions defaultExtensionNs="org.intellij.groovy">
    <membersContributor implementation="org.jetbrains.idea.maven.plugins.groovy.MavenGroovyPomScriptMemberContributor"/>
  </extensions>
</idea-plugin>