NPE: create object

[jburel]

java.lang.Exception: java.lang.IllegalArgumentException: IObject cannot be null.
    at omero.gateway.util.PojoMapper.asDataObject(PojoMapper.java:165)
    at org.openmicroscopy.shoola.env.data.OmeroDataServiceImpl.createDataObject(OmeroDataServiceImpl.java:346)
    at org.openmicroscopy.shoola.env.data.views.calls.DataObjectSaver$1.doCall(DataObjectSaver.java:79)

....
       at org.openmicroscopy.shoola.agents.treeviewer.DataTreeViewerLoader.handleException

QA https://www.openmicroscopy.org/qa2/qa/feedback/33433/

[jburel]

see #391