open fun responseFailed(
    call: Call,
    ioe: IOException,
  ) {
  }

  /**
   * Invoked immediately after a call has completely ended.  This includes delayed consumption
   * of response body by the caller.
   *
   * This method is always invoked after [callStart].
   */
  open fun callEnd(call: Call) {
  }

  /**
   * Invoked when a call fails permanently.
   *