docs: protected List<MessageDescriptor> getWarnings(final ResponseEntity<?> authenticationResponse) {
          val messageDescriptors = new ArrayList<MessageDescriptor>();
  
          val passwordExpirationDate = authenticationResponse.getHeaders().getFirstZonedDateTime("X-CAS-PasswordExpirationDate");
          if (passwordExpirationDate != null) {
              val days = Duration.between(Instant.now(), passwordExpirationDate).toDays();
              messageDescriptors.add(new PasswordExpiringWarningMessageDescriptor(null, days));
          }
  
          val warnings = authenticationResponse.getHeaders().get("X-CAS-Warning");
          if (warnings != null) {
              warnings.stream()
                  .map(DefaultMessageDescriptor::new)
                  .forEach(messageDescriptors::add);
          }
  
          return messageDescriptors;
      }