code: def destination_uris(self):
          
          return [x.path for x in luigi.task.flatten(self.output())]
docs: The fully-qualified URIs that point to your data in Google Cloud
          Storage. Each URI can contain one '*' wildcard character and it must
          come after the 'bucket' name.
  
          Wildcarded destinationUris in GCSQueryTarget might not be resolved
          correctly and result in incomplete data. If a GCSQueryTarget is used to
          pass wildcarded destinationUris be sure to overwrite this property to
          suppress the warning.