If you add a subrepo with no group then use the cli to list that subrepo, it throws a NullPointerException. Below is the stack trace:
java.lang.NullPointerException
at org.opendof.tools.repository.interfaces.da.SubRepositoryNode.toString(SubRepositoryNode.java:134)
at org.opendof.tools.repository.interfaces.da.SubRepositoryNode.toString(SubRepositoryNode.java:138)
at org.opendof.tools.repository.interfaces.cli.ManageController.subrepoList(ManageController.java:347)
at org.opendof.tools.repository.interfaces.cli.InterfaceRepositoryManage.run(InterfaceRepositoryManage.java:145)