@Override
    public int hashCode() {
        return ((key.hashCode() + (from != null ? from.hashCode() : 0)) * 31 + (to != null ? to.hashCode() : 0)) * 31;
    }
@Test
    void requireThatHashCodeIsImplemented() {
        assertEquals(new FeatureRange("key").hashCode(), new FeatureRange("key").hashCode());
    }