Adds Id to Credential Description

src/Microsoft.Identity.Abstractions/ApplicationOptions/CredentialDescription.cs

@@ -15,6 +15,22 @@ namespace Microsoft.Identity.Abstractions
     /// </summary>
     public class CredentialDescription
     {
+        private string? _cachedId;
+
+        /// <summary>
+        /// Gets a unique identifier for a CredentialDescription based on <see cref="SourceType"/> and <see cref="ReferenceOrValue"/>.
+        /// </summary>
+        public string Id
+        {
+            get
+            {
+                if (_cachedId == null)
+                    _cachedId = $"{SourceType}_{Container}_{ReferenceOrValue}";
+
+                return _cachedId;
+            }
+        }
+
         /// <summary>
         /// Type of the source of the credential. This property is used to determine which other properties need
         /// to be provided to describe the credential.

test/Microsoft.Identity.Abstractions.Tests/CredentialDescriptionTest.cs

@@ -1,7 +1,6 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
 
-using System.Security.AccessControl;
 using Xunit;
 
 namespace Microsoft.Identity.Abstractions.ApplicationOptions.Tests
@@ -411,6 +410,27 @@ public void TestValueOrReference(CredentialSource credentialSource)
             Assert.Equal("referenceOrValue", credentialDescription.ReferenceOrValue);
         }
 
+        [Theory]
+        [InlineData(CredentialSource.KeyVault, "KeyVaultUrl", "CertificateName")]
+        [InlineData(CredentialSource.KeyVault, null, "CertificateName")]
+        [InlineData(CredentialSource.KeyVault, "KeyVaultUrl", null)]
+        [InlineData(CredentialSource.KeyVault, null, null)]
+        public void TestId(CredentialSource sourceType, string credentialLocation, string credentialName)
+        {
+            var credentialDescription = new CredentialDescription
+            {
+                SourceType = sourceType,
+                Container = credentialLocation,
+                ReferenceOrValue = credentialName
+            };
 
+            var id = credentialDescription.Id;
+
+            var expectedId = $"{credentialDescription.SourceType}_{credentialDescription.Container}_{credentialDescription.ReferenceOrValue}";
+            Assert.Equal(expectedId, id);
+
+            var cachedId = credentialDescription.Id;
+            Assert.Equal(expectedId, cachedId);
+        }
     }
 }