make multi callbacks

examples/shields/rl/15_train_eval_tune.py

@@ -10,6 +10,7 @@ from ray.tune.logger import UnifiedLogger
 from ray.rllib.models import ModelCatalog
 from ray.tune.logger import pretty_print, UnifiedLogger, CSVLogger
 from ray.rllib.algorithms.algorithm import Algorithm
+from ray.rllib.algorithm.callbacks import make_multi_callbacks
 from ray.air import session
 
 from torch_action_mask_model import TorchActionMaskModel
@@ -78,7 +79,7 @@ def ppo(args):
                                   "shielding": args.shielding is ShieldingConfig.Full or args.shielding is ShieldingConfig.Training,
                                   },)
         .framework("torch")
-        .callbacks([MyCallbacks, ShieldInfoCallback])
+        .callbacks(make_multi_callbacks([MyCallbacks, ShieldInfoCallback]))
         .evaluation(evaluation_config={
                                        "evaluation_interval": 1,
                                         "evaluation_duration": 10,