code: def __check_properties(props):
          # type: (dict) -> None
          
          # Mandatory properties
          mandatory = (
              pelix.remote.PROP_ENDPOINT_ID,
              pelix.remote.PROP_IMPORTED_CONFIGS,
              pelix.constants.OBJECTCLASS,
          )
          for key in mandatory:
              if key not in props:
                  raise ValueError("Missing property: {0}".format(key))
  
          # Export/Import properties
          props_export = (
              pelix.remote.PROP_EXPORTED_CONFIGS,
              pelix.remote.PROP_EXPORTED_INTERFACES,
          )
  
          for key in props_export:
              if key in props:
                  raise ValueError("Export property found: {0}".format(key))
docs: Checks that the given dictionary doesn't have export keys and has
          import keys
  
          :param props: Properties to validate
          :raise ValueError: Invalid properties