The refId value in a custom field appears to be generated based on the name field of the custom field. Can you make this value settable?

Currently, the code is assigning a digit value to the end of the field. If you add, remove, and re-add a field, it appears that the digit can change. The reason it's important is because the refId value is the name of the JSON property in whatever object you are working with. For example, a user object.

There may be other applications that make use of the field. Therefore it is important to be able to control what the field is named. It may also appear in the reports database under that name. So, it is not ideal to have FOLIO assigning the value in an uncontrolled manner.