static get definition() {
    return {}
  }
Getter to retrieve class configuration.
Supports properties:
 - mi18n - a mi18n lookup, (or object of type: lookup for classes supporting multiple types)
 - i18n - for custom / plugin controls, translations for labels can be specified here as an object of locale: label (or an object of type: label for classes supporting multiple types).
 - icon - icon, or object of type: icon for defined types
 - inactive - array of inactive types that shouldn't appear in formBuilder interface (but still be supported for rendering purposes)
@return {Object} configuration