code: function ownProperties (constructor) {
    if (!constructor.hasOwnProperty('_ownProperties')) {
      // @ts-ignore
      constructor._ownProperties = (constructor.hasOwnProperty('properties') && constructor.properties)
        // @ts-ignore
        ? normalizeProperties(constructor.properties)
        : null;
    }
    // @ts-ignore
    return constructor._ownProperties;
  }
docs: Returns a memoized version of the `properties` object for the
  given class. Properties not in object format are converted to at
  least {type}.
  
  @param {(ElementLiteBase | Function | typeof ElementLiteBase)} constructor ElementLiteBase constructor
  @return {Object} Memoized properties object