refactoring objects in preparation for:

refactoring journal database to contain object ids for:
querying journal for objects

bus/src/main/java/de/srsoftware/umbrella/messagebus/events/Event.java

@@ -6,6 +6,7 @@ import static java.util.Optional.*;
 
 import de.srsoftware.tools.Diff;
 import de.srsoftware.tools.Mappable;
+import de.srsoftware.umbrella.core.model.ObjectWithId;
 import de.srsoftware.umbrella.core.model.Translatable;
 import de.srsoftware.umbrella.core.model.UmbrellaUser;
 import java.util.Collection;
@@ -14,15 +15,15 @@ import java.util.Map;
 import java.util.Optional;
 import org.json.JSONObject;
 
-public abstract class Event<Payload extends Mappable> {
+public abstract class Event<Payload extends ObjectWithId> {
 
 	public enum EventType {
 		CREATE,
 		MEMBER_ADDED,
 		UPDATE,
 		DELETE;
-	}
 
+	}
 	private final UmbrellaUser initiator;
 	private final String module;
 	private final Payload payload;
@@ -39,10 +40,10 @@ public abstract class Event<Payload extends Mappable> {
 
 	public Event(UmbrellaUser initiator, String module, Payload payload, Map<String, Object> oldData){
 		this.initiator = initiator;
-		this.module = module;
-		this.payload = payload;
+		this.module    = module;
+		this.payload   = payload;
 		this.eventType = EventType.UPDATE;
-		this.oldData = oldData;
+		this.oldData   = oldData;
 	}
 
 	public abstract Collection<UmbrellaUser> audience();
@@ -98,6 +99,10 @@ public abstract class Event<Payload extends Mappable> {
 		return module;
 	}
 
+	public long objectId() {
+		return payload.id();
+	};
+
 	protected Map<String, Object> oldData() {
 		return oldData;
 	}

bus/src/main/java/de/srsoftware/umbrella/messagebus/events/ItemEvent.java

@@ -36,6 +36,10 @@ public class ItemEvent extends Event<Item>{
 		return t("{user} added \"{item}\" to \"{location}\"", USER,initiator().name(), ITEM, payload().name(), LOCATION, loc);
 	}
 
+	@Override
+	public long objectId() {
+		return payload().id();
+	}
 
 	@Override
 	public Translatable subject() {

bus/src/main/java/de/srsoftware/umbrella/messagebus/events/ProjectEvent.java

@@ -78,6 +78,11 @@ public class ProjectEvent extends Event<Project>{
 		return t("You can view/edit this project at {base_url}/project/{id}/view",ID,payload().id());
 	}
 
+	@Override
+	public long objectId() {
+		return payload().id();
+	}
+
 	@Override
 	public Translatable subject() {
 		return switch (eventType()){

bus/src/main/java/de/srsoftware/umbrella/messagebus/events/TransactionEvent.java

@@ -62,6 +62,11 @@ public class TransactionEvent extends Event<Transaction> {
 		return t("You can view/edit this transaction at {base_url}/account/{id}", ID, payload().accountId());
 	}
 
+	@Override
+	public long objectId() {
+		return payload().id();
+	}
+
 	@Override
 	public Translatable subject() {
 		var user   = initiator().name();

bus/src/main/java/de/srsoftware/umbrella/messagebus/events/WikiEvent.java

@@ -68,6 +68,10 @@ public class WikiEvent extends Event<WikiPage>{
 		return t("You can view/edit this wiki page at {base_url}/wiki/{id}/view",ID,payload().id());
 	}
 
+	@Override
+	public long objectId() {
+		return payload().id();
+	}
 
 	@Override
 	public Translatable subject() {