proxySelector.assertRequests() // No proxy selector requests!
  }

  @Test fun proxySelectorReturnsNull() {
    val nullProxySelector: ProxySelector =
      object : ProxySelector() {
        override fun select(uri: URI): List<Proxy>? {
          assertThat(uri.host).isEqualTo(uriHost)
          return null
        }

        override fun connectFailed(
          uri: URI,
          socketAddress: SocketAddress,

  vararg args: Any,
): String {
  return String.format(Locale.US, format, *args)
}

@Throws(IOException::class)
internal fun BufferedSource.readBomAsCharset(default: Charset): Charset {
  return when (select(UNICODE_BOMS)) {
    0 -> UTF_8
    1 -> UTF_16BE
    2 -> UTF_16LE
    3 -> UTF_32BE
    4 -> UTF_32LE
    -1 -> default
    else -> throw AssertionError()
  }
}

   * ```
   */
  private val subjectAlternativeName: BasicDerAdapter<List<Pair<DerAdapter<*>, Any?>>> =
    generalName.asSequenceOf()

  /**
   * This uses the preceding extension ID to select which adapter to use for the extension value
   * that follows.
   */
  private val extensionValue: BasicDerAdapter<Any?> =
    Adapters.usingTypeHint { typeHint ->
      when (typeHint) {

    if (existingRouteSelection != null && existingRouteSelection.hasNext()) {
      return planConnectToRoute(existingRouteSelection.next())
    }

    // Decide which proxy to use, if any. This may block in ProxySelector.select().
    var newRouteSelector = routeSelector
    if (newRouteSelector == null) {
      newRouteSelector =
        RouteSelector(
          address = address,
          routeDatabase = routeDatabase,

  }

  @Test fun sharesRouteDatabase() {
    val client =
      OkHttpClient.Builder()
        .build()
    val proxySelector: ProxySelector =
      object : ProxySelector() {
        override fun select(uri: URI): List<Proxy> = listOf()

        override fun connectFailed(
          uri: URI,
          socketAddress: SocketAddress,
          e: IOException,
        ) {}
      }

[Moshi](https://github.com/square/moshi) is a handy API for converting between JSON and Java objects. Here we're using it to decode a JSON response from a GitHub API.

Note that `ResponseBody.charStream()` uses the `Content-Type` response header to select which charset to use when decoding the response body. It defaults to `UTF-8` if no charset is specified.

=== ":material-language-kotlin: Kotlin"
    ```kotlin
      private val client = OkHttpClient()

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