code: synchronized List<PageWrapper> getPagesSortedByOffset() {
          return this.pageByOffset
                  .values().stream()
                  .sorted(Comparator.comparingLong(PageWrapper::getOffset))
                  .collect(Collectors.toList());
      }
docs: Gets a new List containing all the PageWrappers in this PageCollection, ordered by their offset.
  @return The List.