@Test
public void subtract() {

    assertEquals(1, AggregationUtils.subtract(2, 1), delta);
    assertEquals(1, AggregationUtils.subtract(2L, 1L), delta);
    assertEquals(1, AggregationUtils.subtract(2F, 1F), delta);
    assertEquals(1, AggregationUtils.subtract(2D, 1D), delta);
    assertEquals(1, AggregationUtils.subtract(2D, 1L), delta);
}