### Question:
Exercise4 { static Integer minimum(final List<Integer> list) { if (list.isEmpty()) throw new IllegalArgumentException("list is empty"); return Lists.foldLeft(list, Integer.MAX_VALUE, Math::min); }    }### Answer:
@Test public void shouldFindMinimum() { final List<Integer> list = asList(1, 2, 3, 4); final Integer expected = 1; final Integer actual = Exercise4.minimum(list); assertEquals(expected, actual); }