Update an Activity Custom Field
You can rename it, change whether it accepts multiple values or not, change the "required" flag, change whether editing its values is restricted to specific Roles, or update the options for a "choices" field type. The updated name will immediately appear in the Close UI and only valid values for the updated `type` will be returned by the Custom Activity API.
The `custom_activity_type_id` and `type` values cannot be changed.