}

  /**
   * Combines four iterators into a single iterator. The returned iterator iterates across the
   * elements in {@code a}, followed by the elements in {@code b}, followed by the elements in
   * {@code c}, followed by the elements in {@code d}. The source iterators are not polled until
   * necessary.
   *

     */
    fun authenticator(authenticator: Authenticator) =
      apply {
        this.authenticator = authenticator
      }

    /** Configure this client to follow redirects. If unset, redirects will be followed. */
    fun followRedirects(followRedirects: Boolean) =
      apply {
        this.followRedirects = followRedirects
      }

    /**

 * equals</i>. That is, {@code a.compareTo(b)} or {@code comparator.compare(a, b)} should equal zero
 * <i>if and only if</i> {@code a.equals(b)}. If this advice is not followed, the resulting map will
 * not correctly obey its specification.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
 *

    The `EventListener` may now see requests and responses interleaved in ways not previously
    permitted. For example, a listener may receive `responseHeadersStart()` followed by
    `requestBodyEnd()`, both on the same call. Such events may be triggered by different threads
    even for a single call.

    Interceptors that rewrite or replace the request body may now inadvertently interfere with