* response body is [closed][ResponseBody]. The recipient of the callback may consume the response
   * body on another thread.
   *
   * Note that transport-layer success (receiving a HTTP response code, headers and body) does not
   * 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,

      return
    }

    try {
      testHttpUrl(testData)
      if (KNOWN_FAILURES.contains(testData.toString())) {
        System.err.println("Expected failure but was success: $testData")
      }
    } catch (e: Throwable) {
      if (KNOWN_FAILURES.contains(testData.toString())) {
        System.err.println("Ignoring known failure: $testData")
        e.printStackTrace()
      } else {

   * leaking resources callers must [close the response body][ResponseBody] or the response.
   *
   * Note that transport-layer success (receiving a HTTP response code, headers and body) does not
   * necessarily indicate application-layer success: `response` may still indicate an unhappy HTTP
   * response code like 404 or 500.
   *

## [Responses](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-response/)

The response answers the request with a code (like 200 for success or 404 for not found), headers, and its own optional body.

## Rewriting Requests

          .setResponseCode(400)
          .setBody("code exchange failed: " + e.getMessage());
    }

    synchronized (this) {
      listeners.remove(state);
    }

    // Success!
    return new MockResponse()
        .setResponseCode(302)
        .addHeader("Location", "https://twitter.com/CuteEmergency/status/789457462864863232");
  }

  public interface Listener {

   * non-null, it should be reported to the user should all further attempts fail.
   *
   * The two values are independent: results can contain both (recoverable error), neither
   * (success), just an exception (permanent failure), or just a plan (non-exceptional retry).
   */
  data class ConnectResult(
    val plan: Plan,
    val nextPlan: Plan? = null,
    val throwable: Throwable? = null,
  ) {

    @Synchronized get() = _failedRoutes.toSet()

  /** Records a failure connecting to [failedRoute]. */
  @Synchronized fun failed(failedRoute: Route) {
    _failedRoutes.add(failedRoute)
  }

  /** Records success connecting to [route]. */
  @Synchronized fun connected(route: Route) {
    _failedRoutes.remove(route)
  }

  /** Returns true if [route] has failed recently and should be avoided. */