I am no expert :-) but at first glance I can see the following issues
1) the cmp-connection-factory entry is not required for a session bean. Also the syntax is wrong.
It should be
<cmp-connection-factory>
<resource-link>DefaultDatasource</resource-link>
</cmp-connection-factory>
instead of
<cmp-connection-factory>DefaultDatasource</cmp-connection-factory>
2)Another thing that is not clear is if <alt-dd>j2ee-deployer-plan.xml</alt-dd> is your openejb-jar.xml file
<module>
<ejb>helloworld-ejb.jar</ejb>
<alt-dd>j2ee-deployer-plan.xml</alt-dd>
</module>
In the alt-dd element you need to give the geronimo specific deployment descriptor of theejb you are trying to deploy i.e. the equivalent of the openejb-jar.xml.
3) A NullPointerException is not at all supposed to occur even if your plans have errors. So you may want to open a JIRA issue.
Hope this helps
Regards
Manu
