@Test
public void testFilter_nullResponseArgument() {

    try {
        new MOfNAggregationFilter(3, 5).doFilter(detectorRequest, null, mockFilterChain);
        fail("Expected NullPointerException to be thrown");
    } catch (NullPointerException e) {
        assertEquals("detectorResponse is marked non-null but is null", e.getMessage());
    }
}