fix missing AccountIDEndpointMode binding (#3013)

Author: lucix-aws

.changelog/3BE795A2-340F-4D5A-B237-8CE604BCB8E9.json

@@ -0,0 +1,8 @@
+{
+    "id": "470a22d1-d830-4095-b12f-990c45e9f951",
+    "type": "bugfix",
+    "description": "Add missing AccountIDEndpointMode binding to endpoint resolution.",
+    "modules": [
+        "service/dynamodb"
+    ]
+}

.changelog/470a22d1d8304095b12f990c45e9f951.json

@@ -41,6 +41,8 @@ public class AwsEndpointBuiltins implements GoIntegration {
             goTemplate("$T(options.DisableMultiRegionAccessPoints)", SdkGoTypes.Aws.Bool);
     private static final GoWriter.Writable BindAccountID =
             goTemplate("resolveAccountID(getIdentity(ctx), options.AccountIDEndpointMode)");
+    private static final GoWriter.Writable BindAccountIDEndpointMode =
+            goTemplate("$T(string(options.AccountIDEndpointMode))", SdkGoTypes.Aws.String);
 
     @Override
     public List<RuntimeClientPlugin> getClientPlugins() {
@@ -55,6 +57,7 @@ public List<RuntimeClientPlugin> getClientPlugins() {
                 .addEndpointBuiltinBinding("AWS::S3::DisableMultiRegionAccessPoints", BindAwsS3DisableMultiRegionAccessPoints)
                 .addEndpointBuiltinBinding("AWS::S3Control::UseArnRegion", BindAwsS3UseArnRegion)
                 .addEndpointBuiltinBinding("AWS::Auth::AccountId", BindAccountID)
+                .addEndpointBuiltinBinding("AWS::Auth::AccountIdEndpointMode", BindAccountIDEndpointMode)
                 .build());
     }