### Question:
FacetRange extends Range<T> { public static <T extends Comparable<? super T>> FacetRange<T> lessThan(final T upperEndpoint) { return new FacetRange<>(null, Bound.exclusive(upperEndpoint)); } private  FacetRange(@Nullable final Bound<T> lowerBound, final Bound<T> upperBound); static FacetRange<T> of(final T lowerEndpoint, final T upperEndpoint); static FacetRange<T> lessThan(final T upperEndpoint); static FacetRange<T> atLeast(final T lowerEndpoint);  }### Answer:
@Test public void buildsFacetRangeLessThan() throws Exception { final Range<Integer> range = FacetRange.lessThan(4); final Bound<Integer> upperBound = range.upperBound(); assertThat(range.lowerBound()).isNull(); assertThat(upperBound.endpoint()).isEqualTo(4); assertThat(upperBound.isExclusive()).isTrue(); }