def CheckInitialized(self):
    super(PropertyEntry, self).CheckInitialized()

    if not (self.external_name or self.import_template or self.export):
      raise bulkloader_errors.InvalidConfiguration(
          'Neither external_name nor import_template nor export specified for '
          'property %s.' % self.property)
Check that all required (combinations) of fields are set.
dataset/ETHPy150Open AppScale/appscale/AppServer/google/appengine/ext/bulkload/bulkloader_parser.py/PropertyEntry.CheckInitialized