code: public static <T> Predicate<T> negate(final Predicate<? super T> predicate) {
          return new Predicate<T>() {
              @Override
              public boolean test(final T testValue) {
                  return !predicate.test(testValue);
              }
          };
      }
docs: Negate an existing predicate's test result.
  
  @param predicate An existing predicate.
  @param <T>       type of the predicate.
  @return new predicate.
  @since 1.5