Looking at the central, it appears that gmaven has changed the groupId.

Old groupId doesn't have 1.1, so this version setting in the POM would
have never worked. I think the intention here is to follow the latest,
so I'm updating the groupId as well.

pom.xml

@@ -231,7 +231,7 @@
           <version>${maven-war-plugin.version}</version>
         </plugin>
         <plugin>
-          <groupId>org.codehaus.groovy.maven</groupId>
+          <groupId>org.codehaus.gmaven</groupId>
           <artifactId>gmaven-plugin</artifactId>
           <version>${gmaven-plugin.version}</version>
         </plugin>
@@ -419,7 +419,7 @@
     <cobertura-maven-plugin.version>2.5.1</cobertura-maven-plugin.version>
     <exec-maven-plugin.version>1.2</exec-maven-plugin.version>
     <findbugs-maven-plugin.version>2.3.1</findbugs-maven-plugin.version>
-    <gmaven-plugin.version>1.1</gmaven-plugin.version>
+    <gmaven-plugin.version>1.3</gmaven-plugin.version>
     <gwt-maven-plugin.version>2.1.0-1</gwt-maven-plugin.version>
     <javancss-maven-plugin.version>2.0</javancss-maven-plugin.version>
     <jdepend-maven-plugin.version>2.0-beta-2</jdepend-maven-plugin.version>