AttributeError: 'ConfigDict' object has no attribute 'optimizer'

Traceback (most recent call last):
File "/usr/lib/python3.10/idlelib/run.py", line 578, in runcode
exec(code, self.locals)
File "/home/v3/Desktop/kitti/train1.py", line 12, in
pipeline.run_train()
File "/home/v3/.local/lib/python3.10/site-packages/open3d/_ml3d/torch/pipelines/semantic_segmentation.py", line 376, in run_train
self.optimizer, self.scheduler = model.get_optimizer(cfg)
File "/home/v3/.local/lib/python3.10/site-packages/open3d/_ml3d/torch/models/randlanet.py", line 354, in get_optimizer
**cfg_pipeline.optimizer)
File "/home/v3/.local/lib/python3.10/site-packages/open3d/_ml3d/utils/config.py", line 244, in __getattr__
return getattr(self._cfg_dict, name)
File "/home/v3/.local/lib/python3.10/site-packages/open3d/_ml3d/utils/config.py", line 27, in __getattr__
raise ex
AttributeError: 'ConfigDict' object has no attribute 'optimizer'

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My code is;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
#Import torch and the model to use for training
import open3d.ml.torch as ml3d
from open3d.ml.torch.models import RandLANet
from open3d.ml.torch.pipelines import SemanticSegmentation

#Read a dataset by specifying the path. We are also providing the cache directory and training split.
dataset = ml3d.datasets.SemanticKITTI(dataset_path='/home/v3/Desktop/kitti/dataset', cache_dir='./logs/cache',training_split=['00', '01', '02', '03', '04', '05', '06', '07', '09', '10'])
#Initialize the RandLANet model with three layers.
model = RandLANet(dim_input=3)
pipeline = SemanticSegmentation(model=model, dataset=dataset, max_epoch=100)
#Run the training
pipeline.run_train()

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Dataset is : sementicKITTI