In the Babel (ONAP A&AI micro-service) we have Java code (inherited from SDC) which calls the ISdcCsarHelper method getVfModulesByVf(String vfCustomizationUuid) in order to obtain a List of Group objects.
For each Group we then call getProperties() expecting the return value to be a Map containing the various Property values.

Early in the development of Babel we tested with a CSAR input file which referenced a non-existent group type. For this CSAR file, the returned Map is empty, although properties are in fact defined for that module Group, and debugging proves that these properties have been parsed from the YAML and are present in a private field of the Group object.

After some investigation it appears that when the group's type is not available (i.e. not defined in the CSAR content) then the group's properties are filtered, resulting in an empty collection.

To replicate the issue create a CSAR file containing a service template. In the groups section of the topology_template create a group containing metadata and properties. Make sure that the type of this group is a type that is not defined elsewhere in the CSAR (specifically the group_types section of the TOSCA).

The above might easily be achieved by selecting a valid CSAR test file and modifying the content by deleting the groups.yml from the Definitions.