I get error: bad request  "Invalid parameter: validity_start_at"

When using API endpoints:

POST or PATCH /learningplan/v1/learningplans/{learning_plan_id}/enrollments/bulk

PATCH /learningplan/v1/learningplans/{learning_plan_id}/enrollments/{user_id}

I get these errors even using the API explorer and selecting the provided models.  By removing the validity start and end fields the endpoint returns success.

Is the documentation wrong?  Do these fields have a different name?