Hi,

I'm trying to build my application for GoogleAppEngine using maven. I've added the following to my pom which should "enhance" my classes after building, as suggested on the DataNucleus documentation

<plugin>
                <groupId>org.datanucleus</groupId>
                <artifactId>maven-datanucleus-plugin</artifactId>
                <version>1.1.4</version>
                <configuration>
                    <log4jConfiguration>${basedir}/log4j.properties</log4jConfiguration>
                    <verbose>true</verbose>
                </configuration>
                <executions>
                    <execution>
                        <phase>process-classes</phase>
                        <goals>
                            <goal>enhance</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>

According to the documentation on GoogleAppEngine, you have the choice to use JDO or JPA, I've chosen to use JPA since I have used it in the past. When I try to build my project (before I upload to GAE) using mvn clean package I get the following output

[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] Failed to resolve artifact.

Missing:
----------
1) javax.jdo:jdo2-api:jar:2.3-ec

  Try downloading the file manually from the project website.

  Then, install it using the command: 
      mvn install:install-file -DgroupId=javax.jdo -DartifactId=jdo2-api -Dversion=2.3-ec -Dpackaging=jar -Dfile=/path/to/file

  Alternatively, if you host your own repository you can deploy the file there: 
      mvn deploy:deploy-file -DgroupId=javax.jdo -DartifactId=jdo2-api -Dversion=2.3-ec -Dpackaging=jar -Dfile=/path/to/file -Durl=[url] -DrepositoryId=[id]

  Path to dependency: 
    1) org.datanucleus:maven-datanucleus-plugin:maven-plugin:1.1.4
    2) javax.jdo:jdo2-api:jar:2.3-ec

----------
1 required artifact is missing.

for artifact: 
  org.datanucleus:maven-datanucleus-plugin:maven-plugin:1.1.4

from the specified remote repositories:
  __jpp_repo__ (file:///usr/share/maven2/repository),
  DN_M2_Repo (http://www.datanucleus.org/downloads/maven2/),
  central (http://repo1.maven.org/maven2)


[INFO] ------------------------------------------------------------------------
[INFO] For more information, run Maven with the -e switch
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 3 seconds
[INFO] Finished at: Sat Apr 03 16:02:39 BST 2010
[INFO] Final Memory: 31M/258M
[INFO] ------------------------------------------------------------------------

Any ideas why I should get such an error? I've searched through my entire source code and I'm not referencing JDO anywhere, so unless the app engine libraries require it, I'm not sure why I get this message.