public static CharMatcher javaIsoControl() {
    return JavaIsoControl.INSTANCE;
  }

  /**
   * Determines whether a character is invisible; that is, if its Unicode category is any of
   * SPACE_SEPARATOR, LINE_SEPARATOR, PARAGRAPH_SEPARATOR, CONTROL, FORMAT, SURROGATE, and
   * PRIVATE_USE according to ICU4J.
   *
   * <p>See also the Unicode Default_Ignorable_Code_Point property (available via ICU).
   *

   * backing sets do. Contains methods to copy the data into a new set which will then remain
   * stable. There is usually no reason to retain a reference of type {@code SetView}; typically,
   * you either use it as a plain {@link Set}, or immediately invoke {@link #immutableCopy} or
   * {@link #copyInto} and forget the {@code SetView} itself.
   *
   * @since 2.0
   */

 *             return createExpensiveGraph(key);
 *           }
 *         });
 * }</pre>
 *
 * <p>Or equivalently,
 *
 * <pre>{@code
 * // In real life this would come from a command-line flag or config file
 * String spec = "maximumSize=10000,expireAfterWrite=10m";
 *
 * LoadingCache<Key, Graph> graphs = CacheBuilder.from(spec)
 *     .removalListener(MY_LISTENER)
 *     .build(

   * X> if we support such a thing? It would be weird or misleading for users to be able to pass
   * `new TypeParameter<@Nullable T>() {}` and have it act as a plain `TypeParameter<T>`, but
   * hopefully no one would do that, anyway. See also the comment on TypeParameter itself.
   *
   * TODO(cpovirk): Elaborate on this / merge with other comment?
   */

  public static CharMatcher javaIsoControl() {
    return JavaIsoControl.INSTANCE;
  }

  /**
   * Determines whether a character is invisible; that is, if its Unicode category is any of
   * SPACE_SEPARATOR, LINE_SEPARATOR, PARAGRAPH_SEPARATOR, CONTROL, FORMAT, SURROGATE, and
   * PRIVATE_USE according to ICU4J.
   *
   * <p>See also the Unicode Default_Ignorable_Code_Point property (available via ICU).
   *

   * using {@link Collections#list}.
   *
   * <p><b>Java 9 users:</b> use {@code enumeration.asIterator()} instead, unless it is important to
   * return an {@code UnmodifiableIterator} instead of a plain {@code Iterator}.
   */
  public static <T extends @Nullable Object> UnmodifiableIterator<T> forEnumeration(
      Enumeration<T> enumeration) {
    checkNotNull(enumeration);

   * using {@link Collections#list}.
   *
   * <p><b>Java 9 users:</b> use {@code enumeration.asIterator()} instead, unless it is important to
   * return an {@code UnmodifiableIterator} instead of a plain {@code Iterator}.
   */
  public static <T extends @Nullable Object> UnmodifiableIterator<T> forEnumeration(
      Enumeration<T> enumeration) {
    checkNotNull(enumeration);