Draft: MVC 1.0 support for message handling

Message.java

public class Message implements Serializable {

  private static final long serialVersionUID = 2518143831776562527L;

  public enum Severity {
    INFO,
    WARN,
    ERROR
  }

  private final Severity severity;
  private final String param;
  private final String text;

  public Message(String text) {
    this(Severity.INFO, text);
  }

  public Message(Severity severity, String text) {
    this(severity, null, text);
  }

  public Message(Severity severity, String param, String text) {
    this.severity = Objects.requireNonNull(severity, "Severity must not be null");
    this.text = Objects.requireNonNull(text, "Text must not be null");
    this.param = param; // optional
  }

  public Severity getSeverity() {
    return severity;
  }

  public String getParam() {
    return param;
  }

  public String getText() {
    return text;
  }
}

Messages.java

@RedirectScoped
public class Messages implements Serializable {

  private static final long serialVersionUID = 6053885126353989270L;

  private final List<Message> messages = new ArrayList<>();

  public Messages add(Message message) {
    messages.add(message);
    return this;
  }

  public List<Message> getAllMessages() {
    return Collections.unmodifiableList(messages);
  }

  public List<Message> getMessages(String param) {
    return messages.stream()
        .filter(message -> param.equals(message.getParam()))
        .collect(Collectors.toList());
  }

}

Severity.SUCCESS could be added