* the returned {@code ListeningExecutorService} never calls the delegate's {@code submit}, {@code
   * invokeAll}, and {@code invokeAny} methods, so any special handling of tasks must be implemented
   * in the delegate's {@code execute} method or by wrapping the returned {@code
   * ListeningExecutorService}.
   *

   * works better than Ordering.natural().nullsFirst() because, if null comes before all other
   * values, it lies outside the submap/submultiset ranges we test, and the variety of tests that
   * exercise null handling fail on those subcollections.
   */
  public abstract static class NullsBefore implements Comparator<@Nullable String>, Serializable {
    /*

   * in which case the signal is a no-op, and the bigger-picture signal is lost unless interrupted
   * threads take special action by participating in the signal-passing game.
   */

  /*
   * Timeout handling is intricate, especially given our ambitious goals:
   * - Avoid underflow and overflow of timeout values when specified timeouts are close to
   *   Long.MIN_VALUE or Long.MAX_VALUE.

  /** Constructor for use by subclasses. */
  protected Converter() {
    this(true);
  }

  /** Constructor used only by {@code LegacyConverter} to suspend automatic null-handling. */
  Converter(boolean handleNullAutomatically) {
    this.handleNullAutomatically = handleNullAutomatically;
  }

  // SPI methods (what subclasses must implement)

  /**

   *
   * @param values a nonempty series of values
   * @throws IllegalArgumentException if {@code values} is empty or contains any non-finite value
   * @deprecated Use {@link Stats#meanOf} instead, noting the less strict handling of non-finite
   *     values.
   */
  @Deprecated
  // com.google.common.math.DoubleUtils
  @GwtIncompatible
  public static double mean(double... values) {

  /** Constructor for use by subclasses. */
  protected Converter() {
    this(true);
  }

  /** Constructor used only by {@code LegacyConverter} to suspend automatic null-handling. */
  Converter(boolean handleNullAutomatically) {
    this.handleNullAutomatically = handleNullAutomatically;
  }

  // SPI methods (what subclasses must implement)

  /**

  //     Ordering.<String>natural().lexicographical();
  public <S extends T> Ordering<Iterable<S>> lexicographical() {
    /*
     * Note that technically the returned ordering should be capable of
     * handling not just {@code Iterable<S>} instances, but also any {@code
     * Iterable<? extends S>}. However, the need for this comes up so rarely
     * that it doesn't justify making everyone else deal with the very ugly
     * wildcard.

      MoreFiles.asCharSink(fooPath, UTF_8).write("foo");

      Path fooSymlink = fs.getPath("symlink");
      Files.createSymbolicLink(fooSymlink, fooPath);

      Path fooHardlink = fs.getPath("hardlink");
      Files.createLink(fooHardlink, fooPath);

      assertThat(MoreFiles.equal(fooPath, fooSymlink)).isTrue();
      assertThat(MoreFiles.equal(fooPath, fooHardlink)).isTrue();

   * works better than Ordering.natural().nullsFirst() because, if null comes before all other
   * values, it lies outside the submap/submultiset ranges we test, and the variety of tests that
   * exercise null handling fail on those subcollections.
   */
  public abstract static class NullsBefore implements Comparator<@Nullable String>, Serializable {
    /*

   *
   * @since 32.0.0
   */
  public static final String OBSERVE_BROWSING_TOPICS = "Observe-Browsing-Topics";

  /**
   * The HTTP <a
   * href="https://wicg.github.io/turtledove/#handling-direct-from-seller-signals">{@code
   * Sec-Ad-Auction-Fetch}</a> header field name.
   *
   * @since 33.0.0
   */
  public static final String SEC_AD_AUCTION_FETCH = "Sec-Ad-Auction-Fetch";

  /**