    @Test
    public void classCastExceptionIsThrown_whenMapHasValueOtherThenStrings() {

        final Map<?, ?> map = ImmutableMap.of("x", "a", "y", new Object());
        assertThatExceptionOfType(ClassCastException.class)
                .isThrownBy(() -> Events.ensureOrderedMapOfStringsToStrings(map));
    }