def METHOD_NAME(self, src: int = 0) -> list:
    trainer = self.trainer_dist_adapter.trainer.trainer
    trainer_class_name = trainer.__class__.__name__
    if not self.has_customized_await_sync_process_group:
        raise RuntimeError(
            f"\"await_sync_process_group\" implementation is required for class {trainer_class_name}"
            f" for customized hierarchical cross-silo."
        )
    return trainer.await_sync_process_group(src)