code: public DistributedVirtualSwitchProductSpec[] queryAvailableDvsSpec(Boolean recommended) throws RuntimeFault, RemoteException {
          return getVimService().queryAvailableDvsSpec(getMOR(), recommended);
      }
docs: This operation returns a list of switch product specifications that are supported by the vCenter Server.
  
  @param recommended If set to true, return only the recommened versions. If set to false, return only the not recommended versions. If unset, return all supported versions.
  @return DistributedVirtualSwitchProductSpec[]
  @throws RuntimeFault
  @throws RemoteException
  @since 6.0