How to detect if the 3d tiles contain normal information?

I have a set of 3D tiles.

It seems the 3D tiles contain normal information. When I zoom into the interiors of the model, my view is not obstructed, like the screenshot.

However, I cannot extract the “material.normalEC” when using the custom shader. The “HAS_NORMALS” is not defined for the 3D tiles. It seems no “normal” attribute can be found in the dataset.

May I know if there is normal info in the data? If yes, how can I extract it in the custom shader?

Many thanks for anyone’s help.

Best regards,