code: public List<Message> getRetrievedHistory()
      {
          int size = size();
          if (size == 0)
              return Collections.emptyList();
          else if (size == 1)
              return Collections.singletonList(history.getValue(0));
          return Collections.unmodifiableList(new ArrayList<>(history.values()));
      }
docs: Returns a List of Messages, sorted starting from newest to oldest, of all message that have already been retrieved
  from Discord with this MessageHistory object using the {@link #retrievePast(int)}, {@link #retrieveFuture(int)}, and
  {@link net.dv8tion.jda.core.entities.MessageChannel#getHistoryAround(String, int)} methods.
  
  @return A List of Messages, sorted newest to oldest.