code: public boolean encloses(Interval other) {
          Objects.requireNonNull(other, "other");
          return start.compareTo(other.start) <= 0 && other.end.compareTo(end) <= 0;
      }
docs: Checks if this interval encloses the specified interval.
  <p>
  This checks if the bounds of the specified interval are within the bounds of this interval.
  An empty interval encloses itself.
  
  @param other  the other interval, not null
  @return true if this interval contains the other interval