Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Data.Entity/System/Data/Metadata/Edm/SafeLinkCollection.cs

@@ -0,0 +1,32 @@
+//---------------------------------------------------------------------
+// <copyright file="SafeLinkCollection.cs" company="Microsoft">
+//      Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+//
+// @owner       [....]
+// @backupOwner [....]
+//---------------------------------------------------------------------
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Data.Metadata.Edm;
+using System.Diagnostics;
+
+namespace System.Data.Metadata.Edm
+{
+    /// <summary>
+    /// This class attempts to make a double linked connection between a parent and child without
+    /// exposing the properties publicly that would allow them to be mutable and possibly dangerous
+    /// in a multithreading environment
+    /// </summary>
+    /// <typeparam name="TParent"></typeparam>
+    /// <typeparam name="TChild"></typeparam>
+    internal class SafeLinkCollection<TParent, TChild> : ReadOnlyMetadataCollection<TChild> where TChild : MetadataItem where TParent : class
+    {
+        public SafeLinkCollection(TParent parent, Func<TChild, SafeLink<TParent>> getLink, MetadataCollection<TChild> children)
+            : base((IList<TChild>)SafeLink<TParent>.BindChildren(parent, getLink, children))
+        {
+        }
+    }
+}