code: public List<String> getMessageList() {
          return messages.map(er -> {
              return requestManager.getMessageManager().toMessageList(requestManager.getUserLocale(), er);
          }).orElse(Collections.emptyList());
      }
docs: Get the list of message text for the errors by user locale. <br>
  Basically these are embedded in exception.
  @return The list of message, resolved by resource. (NotNull, EmptyAllowed)