fix: Update endpoint resolver to handle anonymous credentials when trying to retrieve account IDs

Author: dscpinheiro

generator/.DevConfigs/72b4f8b3-b7e1-496b-a64f-5c4a01528cf0.json

@@ -0,0 +1,11 @@
+{
+    "services": [
+        {
+            "serviceName": "DynamoDBv2",
+            "type": "patch",
+            "changeLogMessages": [
+                "Update endpoint resolver to handle anonymous credentials when trying to retrieve account IDs"
+            ]
+        }
+    ]
+}

generator/ServiceClientGeneratorLib/Generators/Endpoints/EndpointResolver.partial.cs

@@ -25,7 +25,7 @@ private string GetValueSource(Parameter parameter)
                 case "AWS::S3::DisableMultiRegionAccessPoints": return "config.DisableMultiregionAccessPoints";
                 case "AWS::S3::UseGlobalEndpoint": return "config.USEast1RegionalEndpointValue == S3UsEast1RegionalEndpointValue.Legacy";
                 case "AWS::STS::UseGlobalEndpoint": return "false";
-                case "AWS::Auth::AccountId": return "requestContext.Identity is AWSCredentials credentials ? credentials.GetCredentials().AccountId : null";
+                case "AWS::Auth::AccountId": return "requestContext.Identity is AWSCredentials credentials ? credentials.GetCredentials()?.AccountId : null";
                 case "AWS::Auth::AccountIdEndpointMode": return "config.AccountIdEndpointMode.ToString().ToLower()";
                 default: throw new Exception("Unknown builtIn");
             }

sdk/src/Services/DynamoDBv2/Generated/Internal/AmazonDynamoDBEndpointResolver.cs

@@ -54,7 +54,7 @@ protected override EndpointParameters MapEndpointsParameters(IRequestContext req
             result.UseDualStack = config.UseDualstackEndpoint;
             result.UseFIPS = config.UseFIPSEndpoint;
             result.Endpoint = config.ServiceURL;
-            result.AccountId = requestContext.Identity is AWSCredentials credentials ? credentials.GetCredentials().AccountId : null;
+            result.AccountId = requestContext.Identity is AWSCredentials credentials ? credentials.GetCredentials()?.AccountId : null;
             result.AccountIdEndpointMode = config.AccountIdEndpointMode.ToString().ToLower();