doesn't work with eclipse about appengine-maven-plugin HOT 4 CLOSED

Why do you think it i a maven plugin issue and not either an appserver issue, 
or an app issue using non permitted constructs?

Ok, that is very odd. I studied the differences between your demo app in your 
source tree and mine. I then added the <repository> that you have in your pom 
and everything started working. I can no longer reproduce the issue.

Ok, I think I may have found the real issue... 

                    <webResources>
                        <resource>
                            <directory>${basedir}/src/main/webapp/WEB-INF</directory>
                            <filtering>true</filtering>
                            <targetPath>WEB-INF</targetPath>
                        </resource>
                    </webResources>

I think the filtering was mucking with WEB-INF/classes which would explain the 
crazy stack traces.

Sorry for the trouble.