ement.
      */
      headers: {
        type: Object,
        value: function() {
          return {};
        }
      },

      /**
      * iron-ajax request object used to submit the form.
      */
      request: {
        type: Object,
      }
    },

    /**
     * Fired if the form cannot be submitted because it's invalid.
     *
     * @event iron-form-invalid
     */

    /**
     * Fired before the form is submitted.
     *
     * @event iron-form-presubmit
     */

    /**
     * Fired after the f