Declare Private member variables?

Thank you for this program!

Here is my environment:
- [3.1.3 ] System Designer version number
- [MacOS] System Designer platform
- [10.14] Your OS version

How do I represent a private member in the class diagram using System-Designer? Is there support for private member variable declarations?

Recent searches for javascript private members show results that state to use "#" as a prefix for a name in javascript. But I don't know how to do this with JSON schema or JSON.

I can add a property to the Model such as the following:

"myParameter": {
"description": "",
"type": "string",
"readOnly": false,
"mandatory": false,
**"private": true,**
"default": ""
}

But, on the UML class diagram, it still shows "myParameter" with a "+" prefix. Is there an entry (or way) to make it show with a "-" prefix in the UML class diagram?

Any help would be greatly appreciated.

Thanks!