code: def effective_task_id(self):
          
          params = self.param_kwargs
          if 'date' in params and is_closest_date_parameter(self, 'date'):
              params['date'] = self.closest()
              task_id_parts = sorted(['%s=%s' % (k, str(v)) for k, v in params.items()])
              return '%s(%s)' % (self.task_family, ', '.join(task_id_parts))
          else:
              return self.task_id
docs: Replace date in task id with closest date.