code: public Collection<ValidationMessage<Origin>> getMessages(String messageKey) {
  
  		Collection<ValidationMessage<Origin>> result = new ArrayList<ValidationMessage<Origin>>();
  
  		for (ValidationMessage<Origin> message : messages) {
  			if (messageKey.equals(message.getMessageKey())) {
  				result.add(message);
  			}
  		}
  		return result;
  	}
docs: Finds validation messages by the message key.
  
  @param messageKey a message key of the message
  @return a collection of found validation messages