class MaxAggregator implements BiFunction<Integer, Integer, Integer> {
    final public static MaxAggregator INSTANCE = new MaxAggregator();

    private MaxAggregator() {
    }

    @Override
    public @Nullable Integer apply(@Nullable Integer aggregate, @Nullable Integer next) {<FILL_FUNCTION_BODY>}
}

        return next == null || aggregate != null && aggregate >= next ? aggregate : next;
    
<no_super_class>