return // Already closed.
    }
    connection.writeSynReset(id, rstStatusCode)
  }

  override fun cancel() {
    closeLater(ErrorCode.CANCEL)
  }

  /**
   * Abnormally terminate this stream. This enqueues a `RST_STREAM` frame and returns immediately.
   */
  fun closeLater(errorCode: ErrorCode) {
    if (!closeInternal(errorCode, null)) {
      return // Already closed.
    }