code: public boolean contains(Instant instant) {
          Objects.requireNonNull(instant, "instant");
          return start.compareTo(instant) <= 0 && (instant.compareTo(end) < 0 || isUnboundedEnd());
      }
docs: Checks if this interval contains the specified instant.
  <p>
  This checks if the specified instant is within the bounds of this interval.
  If this range has an unbounded start then {@code contains(Instant#MIN)} returns true.
  If this range has an unbounded end then {@code contains(Instant#MAX)} returns true.
  If this range is empty then this method always returns false.
  
  @param instant  the instant, not null
  @return true if this interval contains the instant