Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/System.Runtime.Caching/System/Caching/FileChangeMonitor.cs

@@ -0,0 +1,12 @@
+// <copyright file="FileChangeMonitor.cs" company="Microsoft">
+//   Copyright (c) 2009 Microsoft Corporation.  All rights reserved.
+// </copyright>
+using System;
+using System.Collections.ObjectModel;
+
+namespace System.Runtime.Caching {
+    public abstract class FileChangeMonitor : ChangeMonitor {
+        public abstract ReadOnlyCollection<string> FilePaths { get; }
+        public abstract DateTimeOffset LastModified { get; }
+    }
+}