*     response body exists and will be written immediately.
   */
  @Throws(IOException::class)
  fun writeHeaders(
    responseHeaders: List<Header>,
    outFinished: Boolean,
    flushHeaders: Boolean,
  ) {
    lock.assertNotHeld()

    var flushHeaders = flushHeaders
    this.withLock {
      this.hasResponseHeaders = true

      return false
    }

    @Synchronized override fun onHeaders(
      streamId: Int,
      responseHeaders: List<Header>,
      last: Boolean,
    ): Boolean {
      assertThat(streamId).isEqualTo(2)
      assertThat(last).isTrue()
      events.add(responseHeaders)
      notifyAll()
      return false
    }

    @Synchronized override fun onData(
      streamId: Int,