Fixed bug where blob container get properties throw null exception when access policy was null (Azure#27203)

Author: amnguye

sdk/storage/Azure.Storage.Blobs/CHANGELOG.md

@@ -2,16 +2,10 @@
 
 ## 12.11.0-beta.4 (Unreleased)
 
-### Features Added
 - Added support for progress reporting with DownloadToAsync().
-
-### Breaking Changes
-
-### Bugs Fixed
 - Fixed a bug where BlobBaseClient.DownloadTo() would result in an ObjectDisposedException on .NET Framework in certain network conditions.
 - Added nullable version of `BlobProperties.CopyStatus` called `BlobCopyStatus`, allowing a null value when Storage doesn't return a value.
-
-### Other Changes
+- Fixed a bug where BlobContainerClient.GetProperties() would throw an ArgumentNullException when the AccessPolicy was null
 
 ## 12.11.0-beta.3 (2022-02-07)
 - Added support for service version 2021-04-10.

sdk/storage/Azure.Storage.Blobs/src/Models/BlobSignedIdentifier.cs

@@ -18,10 +18,6 @@ internal BlobSignedIdentifier(string id, BlobAccessPolicy accessPolicy)
             {
                 throw new ArgumentNullException(nameof(id));
             }
-            if (accessPolicy == null)
-            {
-                throw new ArgumentNullException(nameof(accessPolicy));
-            }
 
             Id = id;
             AccessPolicy = accessPolicy;

sdk/storage/Azure.Storage.Blobs/tests/ContainerClientTests.cs

@@ -1136,6 +1136,37 @@ await TestHelper.AssertExpectedExceptionAsync<RequestFailedException>(
                 e => Assert.AreEqual("LeaseNotPresentWithContainerOperation", e.ErrorCode));
         }
 
+        [RecordedTest]
+        public async Task GetAccessPolicyAsync_EmptyAccessPolicy()
+        {
+            await using DisposingContainer test = await GetTestContainerAsync();
+
+            // Arrange
+            PublicAccessType publicAccessType = PublicAccessType.BlobContainer;
+            BlobSignedIdentifier[] signedIdentifiers = new[]
+            {
+                new BlobSignedIdentifier
+                {
+                    Id = GetNewString(),
+                    // Empty Access Policy
+                }
+            };
+
+            // Act
+            Response<BlobContainerInfo> response = await test.Container.SetAccessPolicyAsync(
+                accessType: publicAccessType,
+                permissions: signedIdentifiers
+            );
+
+            // Assert
+            Response<BlobContainerAccessPolicy> getPolicyResponse = await test.Container.GetAccessPolicyAsync();
+            Assert.AreEqual(1, getPolicyResponse.Value.SignedIdentifiers.Count());
+
+            BlobSignedIdentifier acl = getPolicyResponse.Value.SignedIdentifiers.First();
+            Assert.AreEqual(signedIdentifiers[0].Id, acl.Id);
+            Assert.IsNull(acl.AccessPolicy);
+        }
+
         [RecordedTest]
         public async Task GetAccessPolicyAsync_Error()
         {