interface Callback {
    /**
     * Return addresses for a dns query for a single class of IPv4 (A) or IPv6 (AAAA).
     * May be an empty list indicating that the host is unreachable.
     */
    fun onResponse(
      hostname: String,
      addresses: List<InetAddress>,
    )

    /**
     * Returns an error for the DNS query.
     */
    fun onFailure(
      hostname: String,
      e: IOException,
    )

      object : Callback {
        override fun onFailure(
          call: Call,
          e: IOException,
        ) {
          e.printStackTrace()
        }

        override fun onResponse(
          call: Call,
          response: Response,
        ) {
          response.use {
            if (!response.isSuccessful) throw IOException("Unexpected code $response")

          call: Call,
          e: IOException,
        ) {
          exceptionRef.set(e)
          latch.countDown()
        }

        @Throws(IOException::class)
        override fun onResponse(
          call: Call,
          response: Response,
        ) {
          response.close()
          latch.countDown()
        }
      },
    )
    latch.await()

    val okhttp = OkHttpClient()
    val callback =
      object : Callback {
        override fun onFailure(
          call: Call,
          e: IOException,
        ) {}

        override fun onResponse(
          call: Call,
          response: Response,
        ) {
          response.close()
        }
      }
    repeat(10_000) {

      object : Callback {
        override fun onFailure(
          call: Call,
          e: IOException,
        ) {
          println("failed: $e")
        }

        override fun onResponse(
          call: Call,
          response: Response,
        ) {
          println("response: ${response.code}")
          response.close()
        }
      },
    )
  }

      object : Callback {
        override fun onFailure(
          call: Call,
          e: IOException,
        ) {
          continuation.resumeWithException(e)
        }

        override fun onResponse(
          call: Call,
          response: Response,
        ) {
          continuation.resume(response) {
            response.closeQuietly()
          }
        }
      },
    )

    call: Call,
    e: IOException,
  ) {
    responses.add(RecordedResponse(call.request(), null, null, null, e))
    (this as Object).notifyAll()
  }

  @Synchronized
  override fun onResponse(
    call: Call,
    response: Response,
  ) {
    val body = response.body.string()
    responses.add(RecordedResponse(call.request(), response, null, body, null))
    (this as Object).notifyAll()
  }

   * necessarily indicate application-layer success: `response` may still indicate an unhappy HTTP
   * response code like 404 or 500.
   */
  @Throws(IOException::class)
  fun onResponse(
    call: Call,
    response: Response,
  )

 * may ultimately cause the application to slow down or crash.
 *
 * Both this class and [Response] implement [Closeable]. Closing a response simply
 * closes its response body. If you invoke [Call.execute] or implement [Callback.onResponse] you
 * must close this body by calling any of the following methods:
 *
 * * `Response.close()`
 * * `Response.body().close()`
 * * `Response.body().source().close()`
 * * `Response.body().charStream().close()`

        null,
        object : DnsResolver.Callback<List<InetAddress>> {
          override fun onAnswer(
            addresses: List<InetAddress>,
            rCode: Int,
          ) {
            callback.onResponse(hostname, addresses)
          }

          override fun onError(e: DnsResolver.DnsException) {
            callback.onFailure(
              hostname,
              UnknownHostException(e.message).apply {