android/guava/src/com/google/common/base/CharMatcher.java
public static CharMatcher forPredicate(final Predicate<? super Character> predicate) {
    return predicate instanceof CharMatcher ? (CharMatcher) predicate : new ForPredicate(predicate);
  }
public static CharMatcher forPredicate(final Predicate<? super Character> predicate) {
    return predicate instanceof CharMatcher ? (CharMatcher) predicate : new ForPredicate(predicate);
  }
Returns a matcher with identical behavior to the given {@link Character}-based predicate, but
which operates on primitive {@code char} instances instead.