ApplyMetadata is called for all events. Closes GH-3559

docs/events/projections/aggregate-projections.md

@@ -688,6 +688,10 @@ public class TripProjection: SingleStreamProjection<Trip>
 
 ## Working with Event Metadata <Badge type="tip" text="7.12" />
 
+::: info
+As of Marten 7.33, this mechanism executes for every single event in the current event slice in order.
+:::
+
 At any point in an `Apply()` or `Create()` or `ShouldDelete()` method, you can take in either the generic `IEvent` wrapper
 or the specific `IEvent<T>` wrapper type for the specific event. _Sometimes_ though, you may want to automatically take your
 aggregated document with metadata from the very last event the projection is encountering at one time. _If_ you are using

src/Marten/Events/Aggregation/AggregationRuntime.cs

@@ -157,7 +157,11 @@ public async ValueTask ApplyChangesAsync(DocumentSessionBase session,
         {
             Versioning.TrySetVersion(aggregate, lastEvent);
 
-            Projection.ApplyMetadata(aggregate, lastEvent);
+            foreach (var @event in slice.Events())
+            {
+                Projection.ApplyMetadata(aggregate, @event);
+            }
+
         }
 
         // Delete the aggregate *if* it existed prior to these events