Define default GWT version in GWT plugin archetype

The GWT version that is used by Gerrit should be the default for the
GWT plugin.

Change-Id: I22c50e0b91e22d2f591ea5db102ab29bd927bb7b
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>
diff --git a/gerrit-plugin-gwt-archetype/src/main/resources/META-INF/maven/archetype-metadata.xml b/gerrit-plugin-gwt-archetype/src/main/resources/META-INF/maven/archetype-metadata.xml
index 78f2941..6c78cf6 100644
--- a/gerrit-plugin-gwt-archetype/src/main/resources/META-INF/maven/archetype-metadata.xml
+++ b/gerrit-plugin-gwt-archetype/src/main/resources/META-INF/maven/archetype-metadata.xml
@@ -20,7 +20,9 @@
 
     <requiredProperty key="Implementation-Vendor"/>
     <requiredProperty key="Implementation-Url"/>
-    <requiredProperty key="Gwt-Version"/>
+    <requiredProperty key="Gwt-Version">
+      <defaultValue>2.5.1</defaultValue>
+    </requiredProperty>
 
     <requiredProperty key="gerritApiVersion">
       <defaultValue>${defaultGerritApiVersion}</defaultValue>