code: def get_definition_metrics(self, project, definition_id, min_metrics_time=None):
          
          route_values = {}
          if project is not None:
              route_values['project'] = self._serialize.url('project', project, 'str')
          if definition_id is not None:
              route_values['definitionId'] = self._serialize.url('definition_id', definition_id, 'int')
          query_parameters = {}
          if min_metrics_time is not None:
              query_parameters['minMetricsTime'] = self._serialize.query('min_metrics_time', min_metrics_time, 'iso-8601')
          response = self._send(http_method='GET',
                                location_id='d973b939-0ce0-4fec-91d8-da3940fa1827',
                                version='5.0-preview.1',
                                route_values=route_values,
                                query_parameters=query_parameters)
          return self._deserialize('[BuildMetric]', self._unwrap_collection(response))
docs: GetDefinitionMetrics.
          [Preview API] Gets build metrics for a definition.
          :param str project: Project ID or project name
          :param int definition_id: The ID of the definition.
          :param datetime min_metrics_time: The date from which to calculate metrics.
          :rtype: [BuildMetric]