Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/System.IdentityModel/System/IdentityModel/Metadata/EntityId.cs

@@ -0,0 +1,54 @@
+//------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//------------------------------------------------------------
+using System;
+
+namespace System.IdentityModel.Metadata
+{
+    /// <summary>
+    /// Describes the entity id.
+    /// </summary>
+    public class EntityId
+    {
+        const int MaximumLength = 1024;
+        string _id;
+
+        /// <summary>
+        /// The empty constructor.
+        /// </summary>
+        public EntityId()
+            : this(null)
+        {
+        }
+
+        /// <summary>
+        /// Constructs an entity id with the id.
+        /// </summary>
+        /// <param name="id">The id for this instance.</param>
+        public EntityId(string id)
+        {
+            _id = id;
+        }
+
+        /// <summary>
+        /// Gets or sets the id.
+        /// </summary>
+        /// <exception cref="ArgumentException">If length of the id is larger than the maximum length.</exception>
+        public string Id
+        {
+            get { return _id; }
+            set
+            {
+                if (value != null)
+                {
+                    if (value.ToString().Length > MaximumLength)
+                    {
+                        throw DiagnosticUtility.ExceptionUtility.ThrowHelperArgument("value", SR.GetString(SR.ID3199));
+                    }
+                }
+
+                _id = value;
+            }
+        }
+    }
+}