When building the topology information for VMWare through the VMWare Importer (i.e. vmwareTopologyInfo asset field), the code navigates through all the associated networks for each ESX host, and each of them is added to the topology information.
The problem is that the DistributedVirtualPortgroup class extends the Network class on the VIJava API. The idea was to include only the networks, but the algorithm is including also the port groups, and this might include a massive amount of unnecessary information on the topology that could make unreadable the topology map for the VMWare Infrastructure.
For this reason, the port groups should be ignored by default unless the user wants to display them.