ClassNotFoundException on GAE with GWT RPC - google-app-engine

Question

I'm using PlayN to develop a game. It contains a type,GameEvent, defined in my-game-core project. My GWT and GAE code lives in my-game-html, which has my-game-core as a Maven dependency.
Here is the service impl:
package com.mygame.html.server;
import com.mygame.core.event.GameEvent;
import com.mygame.html.client.ServerEventHandlerService;
import com.google.gwt.user.server.rpc.RemoteServiceServlet;
#SuppressWarnings("serial")
public class ServerEventHandlerServiceImpl extends RemoteServiceServlet
implements ServerEventHandlerService {
#Override
public String handleEvent(final GameEvent event) {
return "holy porkchops batman!";
}
}
This compiles just fine. However, when I try to call the service at runtime on the local dev server, I get the following error:
SEVERE: javax.servlet.ServletContext log: Exception while dispatching incoming RPC call
java.lang.NoClassDefFoundError: com/mygame/core/event/GameEvent
...
Caused by: java.lang.ClassNotFoundException: com.mygame.core.event.GameEvent
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at com.google.appengine.tools.development.IsolatedAppClassLoader.loadClass(IsolatedAppClassLoader.java:176)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 39 more
If I take out GameEvent and replace it with a type like String, everything works fine.
What could I be doing wrong here? GameEvent has a default constructor.
Update: Here is pom.xml for the *-html project:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<artifactId>mygame-game</artifactId>
<groupId>com.mygame</groupId>
<version>0.0.1-SNAPSHOT</version>
<relativePath>..</relativePath>
</parent>
<artifactId>mygame-game-html</artifactId>
<packaging>war</packaging>
<name>my game html build</name>
<properties>
<gwt.module>com.mygame.MygameGame</gwt.module>
<gwt.name>mygame</gwt.name>
</properties>
<dependencies>
<dependency>
<groupId>com.mygame</groupId>
<artifactId>mygame-game-core</artifactId>
<version>${project.version}</version>
</dependency>
<dependency>
<groupId>com.googlecode.playn</groupId>
<artifactId>playn-html</artifactId>
<version>1.0-SNAPSHOT</version>
</dependency>
</dependencies>
<build>
<sourceDirectory>src</sourceDirectory>
<outputDirectory>war/WEB-INF/classes</outputDirectory>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.1.1</version>
<configuration>
<warSourceDirectory>war</warSourceDirectory>
</configuration>
</plugin>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>gwt-maven-plugin</artifactId>
<!-- we need class metadata, override PlayN's disabling of such -->
<configuration>
<disableClassMetadata>false</disableClassMetadata>
</configuration>
</plugin>
<plugin>
<artifactId>maven-eclipse-plugin</artifactId>
<version>2.8</version>
<configuration>
<downloadSources>true</downloadSources>
<downloadJavadocs>false</downloadJavadocs>
<wtpversion>2.0</wtpversion>
<additionalBuildcommands>
<buildCommand>
<name>com.google.gwt.eclipse.core.gwtProjectValidator</name>
</buildCommand>
</additionalBuildcommands>
<additionalProjectnatures>
<projectnature>com.google.gwt.eclipse.core.gwtNature</projectnature>
</additionalProjectnatures>
</configuration>
</plugin>
</plugins>
</build>
</project>
Update 2: In war/WEB-INF/lib, I have:
appengine-api-1.0-sdk-1.5.4.jar
appengine-api-1.0-sdk-1.5.5.jar
appengine-api-labs-1.5.4.jar
appengine-api-labs-1.5.5.jar
appengine-jsr107cache-1.5.4.jar
appengine-jsr107cache-1.5.5.jar
datanucleus-appengine-1.0.9.final.jar
datanucleus-core-1.1.5.jar
datanucleus-jpa-1.1.5.jar
geronimo-jpa_3.0_spec-1.1.1.jar
geronimo-jta_1.1_spec-1.1.1.jar
gwt-servlet.jar
jdo2-api-2.3-eb.jar
jsr107cache-1.1.jar

Answer 1

you are missing your dependency my-game-core in the runtime classpath of the jetty that gwt launches.
Did you import your project with mvn eclipse:eclipse into eclipse?
Maybe your runtime classpath still points to your local maven repo, but you already changed your eclipse project (my-game-core). Take a look at your eclipse classpath and make sure it only has the other project on it and not the jar from the repo.
Also check on the classpath tab in your run configuration.