code: public static Stream<Link> getMementoLinks(final String identifier, final SortedSet<Instant> mementos) {
          if (mementos.isEmpty()) {
              return empty();
          }
          return concat(getTimeMap(identifier, mementos.first(), mementos.last()),
                  mementos.stream().map(mementoToLink(identifier)));
      }
docs: Retrieve all of the Memento-related link headers given a collection of datetimes.
  
  @param identifier the public identifier for the resource
  @param mementos a collection of memento values
  @return a stream of link headers