def restore_lr_schedulers(self) -> None:
        """Restores the learning rate scheduler states from the pre-loaded checkpoint."""
        if not self._loaded_checkpoint:
            return

        # restore the lr schedulers
        lr_schedulers = self._loaded_checkpoint["lr_schedulers"]
        for config, lrs_state in zip(self.trainer.lr_scheduler_configs, lr_schedulers):
            config.scheduler.load_state_dict(lrs_state)
Restores the learning rate scheduler states from the pre-loaded checkpoint.
src/lightning/pytorch/trainer/connectors/checkpoint_connector.py