public V merge(
        final Integer key, final V value, final BiFunction<? super V, ? super V, ? extends V> remappingFunction)
    {
        return merge((int)key, value, remappingFunction);
    }
@Test
    void mergeThrowsNullPointerExceptionIfRemappingFunctionIsNull()
    {
        final int key = -9;
        final String value = "abc";

        assertThrowsExactly(NullPointerException.class, () -> cache.merge(key, value, null));
    }