* surprising behavior of {@code toUpperCase()} and {@code toLowerCase()}.
   *
   * @since 16.0
   */
  public static boolean equalsIgnoreCase(CharSequence s1, CharSequence s2) {
    // Calling length() is the null pointer check (so do it before we can exit early).
    int length = s1.length();
    if (s1 == s2) {
      return true;
    }
    if (length != s2.length()) {

  private static final Appendable NASTY_APPENDABLE =
      new Appendable() {
        @Override
        public Appendable append(@Nullable CharSequence csq) throws IOException {
          throw new IOException();
        }

        @Override
        public Appendable append(@Nullable CharSequence csq, int start, int end)
            throws IOException {
          throw new IOException();
        }

        @Override

    <T> void withoutBound(List<T> list) {}

    @SuppressWarnings("unused")
    <T extends Object> void withObjectBound(List<T> list) {}

    @SuppressWarnings("unused")
    <T extends Number & CharSequence> void withUpperBound(List<T> list) {}

    static TypeVariable<?> getTypeVariable(String methodName) throws Exception {
      ParameterizedType parameterType =
          (ParameterizedType)

    <T> void withoutBound(List<T> list) {}

    @SuppressWarnings("unused")
    <T extends Object> void withObjectBound(List<T> list) {}

    @SuppressWarnings("unused")
    <T extends Number & CharSequence> void withUpperBound(List<T> list) {}

    static TypeVariable<?> getTypeVariable(String methodName) throws Exception {
      ParameterizedType parameterType =
          (ParameterizedType)

    }

    private static boolean isEmpty(Object value) {
      // Put types estimated to be the most frequent first.
      if (value instanceof CharSequence) {
        return ((CharSequence) value).length() == 0;
      } else if (value instanceof Collection) {
        return ((Collection<?>) value).isEmpty();
      } else if (value instanceof Map) {

      checkPositionIndexes(off, off + len, str.length());
    }

    @Override
    public Writer append(@CheckForNull CharSequence csq) {
      return this;
    }

    @Override
    public Writer append(@CheckForNull CharSequence csq, int start, int end) {
      checkPositionIndexes(start, end, csq == null ? "null".length() : csq.length());
      return this;
    }

    @Override

     * tolerance is implemented differently: Its implementation avoids calling this toString(Object)
     * method in the first place.)
     */
    requireNonNull(part);
    return (part instanceof CharSequence) ? (CharSequence) part : part.toString();
  }

  private static Iterable<@Nullable Object> iterable(
      @CheckForNull Object first, @CheckForNull Object second, @Nullable Object[] rest) {
    checkNotNull(rest);

    public void checkDefaultValuesForTheseTypes(
        Gender gender,
        Integer integer,
        int i,
        String string,
        CharSequence charSequence,
        List<String> list,
        ImmutableList<Integer> immutableList,
        Map<String, Integer> map,
        ImmutableMap<String, String> immutableMap,
        Set<String> set,

    Object writeReplace() {
      return super.writeReplace();
    }
  }

  private static final class CharSequenceAsList extends AbstractList<Character> {
    private final CharSequence sequence;

    CharSequenceAsList(CharSequence sequence) {
      this.sequence = sequence;
    }

    @Override
    public Character get(int index) {
      checkElementIndex(index, size()); // for GWT

  public void testContainsPattern_apply() {
    Predicate<CharSequence> isFoobar = Predicates.containsPattern("^Fo.*o.*bar$");
    assertTrue(isFoobar.apply("Foxyzoabcbar"));
    assertFalse(isFoobar.apply("Foobarx"));
  }

  @GwtIncompatible // Predicates.containsPattern
  public void testContains_apply() {
    Predicate<CharSequence> isFoobar = Predicates.contains(Pattern.compile("^Fo.*o.*bar$"));