Unable to create successfully a project using GWT-maven-plugin with gwt 2.2

I'm following the documentation of gwt-maven-plugin along with the one on the Google Web Toolkit Blog to have a GWT project mavenized but without success.

Using eclipse 3.6, I create a new maven project using the archetype gwt-maven-plugin 2.1.0-1

I followed instructions found here Google Web Toolkit Blog but it doesn't work. I'm getting an exception:

java.lang.NoClassDefFoundError: com/google/appengine/tools/enhancer/Enhance
Caused by: java.lang.ClassNotFoundException: com.google.appengine.tools.enhancer.Enhance
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
Exception in thread "main" 

I'm using gwt 2.2.0 in GAE 1.4.2 on google eclipse plugin. The same version numbers are used in my pom.xml

Here is the the pom.xml that was generated. It uses 2.1.0 version of gwt but I changed it manually to 2.2.0

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">

  <!-- POM file generated with GWT webAppCreator -->
  <modelVersion>4.0.0</modelVersion>
  <groupId>gwt-comet</groupId>
  <artifactId>gwt-comet-5</artifactId>
  <packaging>war</packaging>
  <version>0.0.1-SNAPSHOT</version>
  <name>GWT Maven Archetype</name>

  <properties>
    <!-- Convenience property to set the GWT version -->
    <gwtVersion>2.2.0</gwtVersion>
    <!-- GWT needs at least java 1.5 -->
    <maven.compiler.source>1.5</maven.compiler.source>
    <maven.compiler.target>1.5</maven.compiler.target>
    <webappDirectory>${project.build.directory}/${project.build.finalName}</webappDirectory>
  </properties>

  <dependencies>
    <dependency>
      <groupId>com.google.gwt</groupId>
      <artifactId>gwt-servlet</artifactId>
      <version>2.2.0</version>
      <scope>runtime</scope>
    </dependency>
    <dependency>
      <groupId>com.google.gwt</groupId>
      <artifactId>gwt-user</artifactId>
      <version>2.2.0</version>
      <scope>provided</scope>
    </dependency>  
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.7</version>
      <scope>test</scope>
    </dependency>
  </dependencies>

  <build>
    <!-- Generate compiled stuff in the folder used for developing mode -->
    <outputDirectory>${webappDirectory}/WEB-INF/classes</outputDirectory>

    <plugins>

      <!-- GWT Maven Plugin -->
      <plugin>
        <groupId>org.codehaus.mojo</groupId>
        <artifactId>gwt-maven-plugin</artifactId>
        <version>2.1.0-1</version>
        <executions>
          <execution>
            <goals>
              <goal>compile</goal>
              <goal>test</goal>
              <goal>i18n</goal>
              <goal>generateAsync</goal>
            </goals>
          </execution>
        </executions>
        <!-- Plugin configuration. There are many available options, see gwt-maven-plugin 
          documentation at codehaus.org -->
        <configuration>
          <runTarget>Comet.html</runTarget>
          <hostedWebapp>${webappDirectory}</hostedWebapp>
          <i18nMessagesBundle>fr.client.Messages</i18nMessagesBundle>
        </configuration>
      </plugin>

      <!-- Copy static web files before executing gwt:run -->
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-war-plugin</artifactId>
        <version>2.1.1</version>
        <executions>
          <execution>
            <phase>compile</phase>
            <goals>
              <goal>exploded</goal>
            </goals>
          </execution>
        </executions>
        <configuration>
          <webappDirectory>${webappDirectory}</webappDirectory>
        </configuration>
      </plugin>

    </plugins>
  </build>

</project>

I haven't been using it with GAE, but there's a newer version of gwt-maven-plugin for 2.2. Set it to 2.2.0 or remove version tag and it will fetch the latest one. You also don't have any dependency for GAE in your pom.