toObject(options) {
    // `[].concat` coerces the return value into a vanilla JS array, rather
    // than a Mongoose array.
    return [].concat(this.map(function(doc) {
      if (doc == null) {
        return null;
      }
      if (typeof doc.toObject !== 'function') {
        return doc;
      }
      return doc.toObject(options);
    }));
  }
Returns a native js Array of plain js objects

#### Note:

_Each sub-document is converted to a plain object by calling its `#toObject` method._

@param {Object} [options] optional options to pass to each documents `toObject` method call during conversion
@return {Array}
@method toObject
@api public
@memberOf MongooseDocumentArray