Implement ResolvableTypeProvider to circumvent type erasure

src/main/java/de/thm/arsnova/event/CrudEvent.java

@@ -2,8 +2,10 @@ package de.thm.arsnova.event;
 
 import de.thm.arsnova.model.Entity;
 import org.springframework.context.ApplicationEvent;
+import org.springframework.core.ResolvableType;
+import org.springframework.core.ResolvableTypeProvider;
 
-public abstract class CrudEvent<E extends Entity> extends ApplicationEvent {
+public abstract class CrudEvent<E extends Entity> extends ApplicationEvent implements ResolvableTypeProvider {
 	public CrudEvent(final E source) {
 		super(source);
 	}
@@ -12,4 +14,9 @@ public abstract class CrudEvent<E extends Entity> extends ApplicationEvent {
 	public E getSource() {
 		return (E) super.getSource();
 	}
+
+	@Override
+	public ResolvableType getResolvableType() {
+		return ResolvableType.forClassWithGenerics(getClass(), source.getClass());
+	}
 }