@Override
    public String toString() {
        return "{NDRTDT " + getName() + " id=" + getId() + " target=" + target + " [" + target.getClass().getSimpleName() + "]}";
    }
Model for ReferenceDataType which is more suitable when
we want to end up with NewDocumentType as target type.

@author arnej
config-model/src/main/java/com/yahoo/documentmodel/NewDocumentReferenceDataType.java