@Override
    public RangeBoundary getHighBoundary() {
        return highBoundary;
    }
@Test
    void getHighBoundary() {
        final Range.RangeBoundary highBoundary = Range.RangeBoundary.CLOSED;
        final RangeImpl rangeImpl = new RangeImpl(Range.RangeBoundary.OPEN, 10, 15, highBoundary);
        assertThat(rangeImpl.getHighBoundary()).isEqualTo(highBoundary);
    }