static icon(type) {
    // @todo - support for `${css_prefix_text}${attr.name}` - is this for inputSets? Doesnt look like it but can't see anything else that sets attr.name?
    // https://formbuilder.online/docs/formBuilder/options/inputSets/
    const def = this.definition
    if (def && typeof def.icon === 'object') {
      return def.icon[type]
    }
    return def.icon
  }
Retrieve the icon for a control type
@param {String} type
@return {String} icon