docs: @GwtIncompatible // Class.isInstance
    public static <T> Iterable<T> filter(final Iterable<?> unfiltered, final Class<T> desiredType) {
      checkNotNull(unfiltered);
      checkNotNull(desiredType);
      return new FluentIterable<T>() {
        @Override
        public Iterator<T> iterator() {
          return Iterators.filter(unfiltered.iterator(), desiredType);
        }
      };
    }