separates classes to files

src/Umbraco.Core/Events/IEventAggregator.cs

@@ -22,27 +22,4 @@ namespace Umbraco.Core.Events
         Task PublishAsync<TNotification>(TNotification notification, CancellationToken cancellationToken = default)
             where TNotification : INotification;
     }
-
-    /// <summary>
-    /// A marker interface to represent a notification.
-    /// </summary>
-    public interface INotification
-    {
-    }
-
-    /// <summary>
-    /// Defines a handler for a notification.
-    /// </summary>
-    /// <typeparam name="TNotification">The type of notification being handled.</typeparam>
-    public interface INotificationHandler<in TNotification>
-        where TNotification : INotification
-    {
-        /// <summary>
-        /// Handles a notification
-        /// </summary>
-        /// <param name="notification">The notification</param>
-        /// <param name="cancellationToken">The cancellation token.</param>
-        /// <returns>A <see cref="Task"/> representing the asynchronous operation.</returns>
-        Task HandleAsync(TNotification notification, CancellationToken cancellationToken);
-    }
 }

src/Umbraco.Core/Events/INotification.cs

@@ -0,0 +1,12 @@
+// Copyright (c) Umbraco.
+// See LICENSE for more details.
+
+namespace Umbraco.Core.Events
+{
+    /// <summary>
+    /// A marker interface to represent a notification.
+    /// </summary>
+    public interface INotification
+    {
+    }
+}

src/Umbraco.Core/Events/INotificationHandler.cs

@@ -0,0 +1,24 @@
+// Copyright (c) Umbraco.
+// See LICENSE for more details.
+
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Umbraco.Core.Events
+{
+    /// <summary>
+    /// Defines a handler for a notification.
+    /// </summary>
+    /// <typeparam name="TNotification">The type of notification being handled.</typeparam>
+    public interface INotificationHandler<in TNotification>
+        where TNotification : INotification
+    {
+        /// <summary>
+        /// Handles a notification
+        /// </summary>
+        /// <param name="notification">The notification</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
+        /// <returns>A <see cref="Task"/> representing the asynchronous operation.</returns>
+        Task HandleAsync(TNotification notification, CancellationToken cancellationToken);
+    }
+}