* Implementations must quickly dispatch callbacks to avoid creating a bottleneck.
 *
 * While [onReset] may occur at any time, the following callbacks are expected in order,
 * correlated by stream ID.
 *
 *  * [onRequest]
 *  * [onHeaders] (unless canceled)
 *  * [onData] (optional sequence of data frames)
 *

  private lateinit var serverIpv6: MockWebServer

  private val listener = RecordingEventListener()
  private lateinit var client: OkHttpClient
  private lateinit var url: HttpUrl

  /**
   * This is mutable and order matters. By default, it contains [IPv4, IPv6]. Tests may manipulate
   * it to prefer IPv6.
   */
  private var dnsResults = listOf<InetAddress>()

  @BeforeEach
  internal fun setUp() {

      }
    }

  companion object {
    /**
     * The "mixed" subtype of "multipart" is intended for use when the body parts are independent
     * and need to be bundled in a particular order. Any "multipart" subtypes that an implementation
     * does not recognize must be treated as being of subtype "mixed".
     */
    @JvmField
    val MIXED = "multipart/mixed".toMediaType()

    /**

  private var streams: Streams? = null

  /** Outgoing pongs in the order they should be written. */
  private val pongQueue = ArrayDeque<ByteString>()

  /** Outgoing messages and close frames in the order they should be written. */
  private val messageAndCloseQueue = ArrayDeque<Any>()

 *  New: Make `ResponseBody.string()` and `ResponseBody.charStream()` BOM-aware. If your HTTP
    response body begins with a [byte order mark][bom] it will be consumed and used to select a
    charset for the remaining bytes. Most applications should not need a byte order mark.

 *  New: Upgrade to Okio 1.11.0.

     ```xml
     <dependency>
       <groupId>com.squareup.okio</groupId>

 * host platform (like Android). In July 2018 Android had 134 trusted root certificates for its HTTP
 * clients to trust.
 *
 * For example, in order to establish a secure connection to `https://www.squareup.com/`,
 * these three certificates are used.
 *
 * ```
 * www.squareup.com certificate:
 *
 * Common Name: www.squareup.com

import okhttp3.CallEvent.SecureConnectEnd
import okhttp3.CallEvent.SecureConnectStart
import org.junit.jupiter.api.Assertions.fail

open class RecordingEventListener(
  /**
   * An override to ignore the normal order that is enforced.
   * EventListeners added by Interceptors will not see all events.
   */
  private val enforceOrder: Boolean = true,
) : EventListener() {
  val eventSequence: Deque<CallEvent> = ConcurrentLinkedDeque()

        if (!"Vary".equals(name(i), ignoreCase = true)) {
          continue
        }

        val value = value(i)
        if (result == null) {
          result = TreeSet(String.CASE_INSENSITIVE_ORDER)
        }
        for (varyField in value.split(',')) {
          result.add(varyField.trim())
        }
      }
      return result ?: emptySet()
    }

    /**

              SynchronousQueue(),
              threadFactory("$okHttpName Dispatcher", false),
            )
        }
        return executorServiceOrNull!!
      }

  /** Ready async calls in the order they'll be run. */
  private val readyAsyncCalls = ArrayDeque<AsyncCall>()

  /** Running asynchronous calls. Includes canceled calls that haven't finished yet. */
  private val runningAsyncCalls = ArrayDeque<AsyncCall>()

![Interceptors Diagram](../assets/images/******@****.***)

### Application Interceptors