sample.java

    interface Comparator<T> {
        boolean lt(T left, T right);
    }

    static Object NULL = new Object();

    static class LtInf implements Comparator<Object> {

        @Override
        public boolean lt(Object left, Object right) {
            if (left != NULL) {
              if (right != NULL) {
                return ((Integer) left) < ((Integer) right); // These casts are provably safe in Kotlin
              } else
                return true;
            } else
              return false;
        }
    }


    static <T> Object max(Iterable<? extends T> ts, Comparator<? super T> lt) {
      Object max = NULL;
      for (T t : ts) {
        Object m = max;
        if (m != NULL) {
          if (lt.lt((T) m, t)) // This cast is provably safe in Kotlin
            max = t;
        } else {
           max = t;
        }
      }
      return max;
    }

    public static void main(String[] args) {
       Iterable<Object> ts = Lists.newArrayList(1, NULL, 5);
       System.out.println(max(ts, new LtInf()));
    }