return new Joiner(separator);
  }

  /** Returns a joiner which automatically places {@code separator} between consecutive elements. */
  public static Joiner on(char separator) {
    return new Joiner(String.valueOf(separator));
  }

  private final String separator;

  private Joiner(String separator) {
    this.separator = checkNotNull(separator);
  }

  private Joiner(Joiner prototype) {

    return new Joiner(separator);
  }

  /** Returns a joiner which automatically places {@code separator} between consecutive elements. */
  public static Joiner on(char separator) {
    return new Joiner(String.valueOf(separator));
  }

  private final String separator;

  private Joiner(String separator) {
    this.separator = checkNotNull(separator);
  }

  private Joiner(Joiner prototype) {

  }

  private static final Joiner joiner = Joiner.on(", ");

  @Override
  protected void assertMoreInvariants(Map<K, V> map) {
    // TODO: can these be moved to MapInterfaceTest?
    for (Entry<K, V> entry : map.entrySet()) {
      assertEquals(entry.getKey() + "=" + entry.getValue(), entry.toString());
    }

    assertEquals("{" + joiner.join(map.entrySet()) + "}", map.toString());

        }
        String prefix = (moduleName == null) ? (option + ' ') : (option + ' ' + moduleName + '=');
        StringJoiner joiner = new StringJoiner(File.pathSeparator, prefix, "");
        joiner.setEmptyValue("");
        for (Path p : paths) {
            joiner.add(p.toString());
        }
        return joiner.toString();
    }

    @Override
    public String toString() {
        return "PathType[" + id() + "]";

   * {@code joiner}.
   *
   * <p><b>{@code Stream} equivalent:</b> {@code joiner.join(stream.iterator())}, or, if you are not
   * using any optional {@code Joiner} features, {@code
   * stream.collect(Collectors.joining(delimiter)}.
   *
   * @since 18.0
   */
  public final String join(Joiner joiner) {
    return joiner.join(this);
  }

  /**

          .put(OptionalDouble.class, OptionalDouble.empty())
          .put(UUID.class, UUID.randomUUID())
          // common.base
          .put(CharMatcher.class, CharMatcher.none())
          .put(Joiner.class, Joiner.on(','))
          .put(Splitter.class, Splitter.on(','))
          .put(com.google.common.base.Optional.class, com.google.common.base.Optional.absent())
          .put(Predicate.class, Predicates.alwaysTrue())

          .put(Locale.class, Locale.US)
          .put(UUID.class, UUID.randomUUID())
          // common.base
          .put(CharMatcher.class, CharMatcher.none())
          .put(Joiner.class, Joiner.on(','))
          .put(Splitter.class, Splitter.on(','))
          .put(com.google.common.base.Optional.class, com.google.common.base.Optional.absent())
          .put(Predicate.class, Predicates.alwaysTrue())

 * (note: even fixed-length splitters).
 *
 * <p>Splitter instances are thread-safe immutable, and are therefore safe to store as {@code static
 * final} constants.
 *
 * <p>The {@link Joiner} class provides the inverse operation to splitting, but note that a
 * round-trip between the two should be assumed to be lossy.
 *
 * <p>See the Guava User Guide article on <a

   *       versa.
   *   <li>Inequality check is not performed against state mutation methods such as {@link
   *       List#add}, or functional update methods such as {@link
   *       com.google.common.base.Joiner#skipNulls}.
   *   <li>If the constructor or factory method used to construct instance takes a parameter that
   *       {@link AbstractPackageSanityTests} doesn't know how to construct, the test will fail.

   * cases where {@link Collection#contains} might throw {@link NullPointerException} or {@link
   * ClassCastException}.
   */
  // <? extends @Nullable Object> instead of <?> because of Kotlin b/189937072, discussed in Joiner.
  public static boolean contains(
      Iterable<? extends @Nullable Object> iterable, @CheckForNull Object element) {
    if (iterable instanceof Collection) {
      Collection<?> collection = (Collection<?>) iterable;