code: public static <E extends Comparable<? super E>>
        Collector<Range<E>, ?, ImmutableRangeSet<E>> toImmutableRangeSet() {
      return CollectCollectors.toImmutableRangeSet();
    }
docs: Returns a {@code Collector} that accumulates the input elements into a new {@code
  ImmutableRangeSet}. As in {@link Builder}, overlapping ranges are not permitted and adjacent
  ranges will be merged.
  
  @since 23.1