docs: public void parseMessages() {
      for (Element messageElement : rootElement.elements("message")) {
        String id = messageElement.attribute("id");
        String messageName = messageElement.attribute("name");
  
        Expression messageExpression = null;
        if (messageName != null) {
          messageExpression = expressionManager.createExpression(messageName);
        }
  
        MessageDefinition messageDefinition = new MessageDefinition(this.targetNamespace + ":" + id, messageExpression);
        this.messages.put(messageDefinition.getId(), messageDefinition);
      }
    }