Some requests will have a cached response. When this cached response isn’t fresh, OkHttp can do a _conditional GET_ to download an updated response if it’s newer than what’s cached. This requires headers like `If-Modified-Since` and `If-None-Match` to be added.

## Rewriting Responses

     </dependency>
     ```

 *  Fix: Gracefully recover from a failure to rebuild the cache journal.
 *  Fix: Don't corrupt cache entries when a cache entry is evicted while it is
    being updated.
 *  Fix: Make logging more consistent throughout OkHttp.
 *  Fix: Log plaintext bodies only. This uses simple heuristics to differentiate
    text from other data.

    assertThat(read).isEqualTo(8192)

    // Make a second call that should transmit the response headers. The response body won't be
    // transmitted until the flow-control window is updated from the first request.
    val call2 = client.newCall(Request(server.url("/")))
    val response2 = call2.execute()
    assertThat(response2.code).isEqualTo(200)

private val BROWSER_COMPATIBLE_DATE_FORMAT_STRINGS =
  arrayOf(
    // HTTP formats required by RFC2616 but with any timezone:
    // RFC 822, updated by RFC 1123 with any TZ.
    "EEE, dd MMM yyyy HH:mm:ss zzz",
    // RFC 850, obsoleted by RFC 1036 with any TZ.
    "EEEE, dd-MMM-yy HH:mm:ss zzz",
    // ANSI C's asctime() format
    "EEE MMM d HH:mm:ss yyyy",

 *    cache.
 *
 * Sometimes a request will result in a conditional cache hit. If the cache contains a stale copy of
 * the response, the client will issue a conditional `GET`. The server will then send either
 * the updated response if it has changed, or a short 'not modified' response if the client's copy
 * is still valid. Such responses increment both the network count and hit count.
 *

     * initialized by the time those parts of `<clinit>()` run. Guarded by CipherSuite.class.
     */
    private val INSTANCES = mutableMapOf<String, CipherSuite>()

    // Last updated 2016-07-03 using cipher suites from Android 24 and Java 9.

    // @JvmField val TLS_NULL_WITH_NULL_NULL = init("TLS_NULL_WITH_NULL_NULL", 0x0000)
    @JvmField val TLS_RSA_WITH_NULL_MD5 = init("SSL_RSA_WITH_NULL_MD5", 0x0001)

 *  **Changing a HttpUrl’s scheme now tracks the default port.** We had a bug
    where changing a URL from `http` to `https` would leave it on port 80.

 *  **Okio has been updated to 1.6.0.**
     ```xml
     <dependency>
       <groupId>com.squareup.okio</groupId>
       <artifactId>okio</artifactId>
       <version>1.6.0</version>
     </dependency>
     ```

    abstract fun onStream(stream: Http2Stream)

    /**
     * Notification that the connection's peer's settings may have changed to [settings].
     * Implementations should take appropriate action to handle the updated settings.
     *
     * Methods to this method may be made concurrently with [onStream]. But a calls to this method
     * are serialized.
     */
    open fun onSettings(
      connection: Http2Connection,

   * contains space-separated values: a state, a key, and optional state-specific values.
   *
   *   o DIRTY lines track that an entry is actively being created or updated. Every successful
   *     DIRTY action should be followed by a CLEAN or REMOVE action. DIRTY lines without a matching
   *     CLEAN or REMOVE indicate that temporary files may need to be deleted.
   *

  }

  @AfterEach
  @Throws(Exception::class)
  fun tearDown() {
    TimeZone.setDefault(originalDefault)
  }

  @Test
  @Throws(Exception::class)
  fun parseStandardFormats() {
    // RFC 822, updated by RFC 1123 with GMT.
    assertThat("Thu, 01 Jan 1970 00:00:00 GMT".toHttpDateOrNull()!!.time).isEqualTo(0L)
    assertThat("Fri, 06 Jun 2014 12:30:30 GMT".toHttpDateOrNull()!!.time).isEqualTo(1402057830000L)