before the response starts. With duplex, request and response bodies are transmitted
    simultaneously. This can be used to implement interactive conversations within a single HTTP
    call.

    Create duplex calls by overriding the new `RequestBody.isDuplex()` method to return true.
    This simple option dramatically changes the behavior of the request body and of the entire
    call.

      }

    /**
     * Sets the socket factory used to create connections. OkHttp only uses the parameterless
     * [SocketFactory.createSocket] method to create unconnected sockets. Overriding this method,
     * e. g., allows the socket to be bound to a specific local address.
     *
     * If unset, the [system-wide default][SocketFactory.getDefault] socket factory will be used.
     */

   */
  final class WriteThroughEntry extends SimpleEntry<K, V> {
    WriteThroughEntry(K key, V value) {
      super(key, value);
    }

    /*
     * We inherit equals() and hashCode() instead of overriding them to use keyEquivalence and
     * valueEquivalence.
     */

    @Override
    public V setValue(V newValue) {
      put(getKey(), newValue);

   * broadly guaranteed, but it is observed to be true for OpenJDK 1.7. It also can't be guaranteed
   * that the method isn't inadvertently <i>oversizing</i> the returned set.
   *
   * @param expectedSize the number of elements you expect to add to the returned set
   * @return a new, empty {@code LinkedHashSet} with enough capacity to hold {@code expectedSize}