code: def getGerritChanges(props):
          
          if 'gerrit_changes' in props:
              return props.getProperty('gerrit_changes')
  
          if 'event.change.number' in props:
              return [{
                  'change_id': props.getProperty('event.change.number'),
                  'revision_id': props.getProperty('event.patchSet.number')
              }]
          return []
docs: Get the gerrit changes
  
              This method could be overridden if really needed to accommodate for other
              custom steps method for fetching gerrit changes.
  
              :param props: an IProperty
  
              :return: (optionally via deferred) a list of dictionary with at list
                  change_id, and revision_id,
                  which format is the one accepted by the gerrit REST API as of
                  /changes/:change_id/revision/:revision_id paths (see gerrit doc)