MyLabel.java

public enum MyLabel implements LabelId {
    FIRST_NAME("firstName"), LAST_NAME("lastName");

    private final String key;

    MyLabel(String key) {
        this.key = "{" + key + "}";
    }

    @Override
    public String getId() {
        return key;
    }

    @Override
    public String toString() {
        return key;
    }
}