JSDoc does not parse type *= correctly

[weswigham]

TypeScript Version: 2.7.0-dev.201xxxxx

Code

  /**
   * @override
   * @param {symbol} eventType
   * @param {*=} eventData
   */
  dispatchEventToListeners(eventType, eventData) {
    if (!this._listeners || !this._listeners.has(eventType))
      return;

    var event = /** @type {!Common.Event} */ ({data: eventData});
    var listeners = this._listeners.get(eventType).slice(0);
    for (var i = 0; i < listeners.length; ++i)
      listeners[i].listener.call(listeners[i].thisObject, event);
  }

Expected behavior:
No errors, type for eventData is any | undefined.

Actual behavior:

front_end/common/Object.js(103,14): error TS1110: Type expected.

(A parse error on *= - a valid jsdoc type (an arity-optional anything))