I want to repeat my previous comment since that one is outdated and therefore easier to miss.

Me: "This should be in the constructor."

@stnguyen09: "That isn't consistent with how we're doing things."

Me: "Many things that are not saved on state and cannot be changed by the user are set in the constructor. For example, in `Property.js`, `this.onchange = options.onchange` or `this._displayName = options.displayName` and others."