Defualt interface methods for Overlay Message

src/de/tudarmstadt/maki/simonstrator/api/component/overlay/OverlayMessage.java

@@ -34,10 +34,18 @@ public interface OverlayMessage extends Message {
 		throw new UnsupportedOperationException();
 	}
 
+	default public boolean hasUUID() {
+		return false;
+	}
+
 	/**
 	 * @return The message creation timestamp
 	 */
 	default public long getTimestamp() {
 		throw new UnsupportedOperationException();
 	}
+
+	default public boolean hasTimestamp() {
+		return false;
+	}
 }