Question I want to know about BehaviorParameters.

hello,I tried to understand the meaning of BehaviorParameters.VectorActionDescriptions.
（src comment: The list of strings describing what the actions correspond to.）
In the hierarchy,I can't change the value.
If modified by code:
BehaviorParameters.BrainParameters.VectorActionDescriptions = null; ->train error
BehaviorParameters.BrainParameters.VectorActionDescriptions = new string[n]; ->train error
BehaviorParameters.BrainParameters.VectorActionDescriptions = new string[1]{""}; ->working
BehaviorParameters.BrainParameters.VectorActionDescriptions = new string[n]{"1","2",....}; ->working

Please tell me the details to use the determined value.

 

Under the constraints of my existing code, agent components have to be dynamically added to the code.
Please refer to：https://forum.unity.com/threads/academy-instance-environmentstep-did-not-work.889663/
If I don’t set a value for the BehaviorParameters.VectorActionDescriptions,the training cannot start.