fix(cfn-include): correctly handle the 'AWS::CloudFormation::CustomResource' resource type (#10415)

The resource type 'AWS::CloudFormation::CustomResource' corresponds to the class CfnCustomResource.
However, that class is automatically generated, and quite useless; it only supports one property, ServiceToken.
It does not support passing in an arbitrary collection of properties,
like custom resources in CloudFormation do.
As a result, cfn-include would "lose" all properties of resources of type 'AWS::CloudFormation::CustomResource'
other than ServiceToken.
Fix the problem by handling this resource type with the CfnResource class,
that does support an arbitrary collection of properties.

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: skinny85

packages/@aws-cdk/cloudformation-include/lib/cfn-include.ts

@@ -634,7 +634,11 @@ export class CfnInclude extends core.CfnElement {
       l1Instance = this.createNestedStack(logicalId, cfnParser);
     } else {
       const l1ClassFqn = cfn_type_to_l1_mapping.lookup(resourceAttributes.Type);
-      if (l1ClassFqn) {
+      // The AWS::CloudFormation::CustomResource type corresponds to the CfnCustomResource class.
+      // Unfortunately, it's quite useless; it only has a single property, ServiceToken.
+      // For that reason, even the CustomResource class from @core doesn't use it!
+      // So, special-case the handling of this one resource type
+      if (l1ClassFqn && resourceAttributes.Type !== 'AWS::CloudFormation::CustomResource') {
         const options: cfn_parse.FromCloudFormationOptions = {
           parser: cfnParser,
         };

packages/@aws-cdk/cloudformation-include/test/test-templates/custom-resource-with-attributes.json

@@ -27,9 +27,9 @@
       "DependsOn": [ "CustomResource" ]
     },
     "CustomResource": {
-      "Type": "AWS::MyService::AnotherCustom",
+      "Type": "AWS::CloudFormation::CustomResource",
       "Properties": {
-        "CustomProp": "CustomValue",
+        "ServiceToken": "CustomValue",
         "CustomFuncProp": {
           "Ref": "AWS::NoValue"
         }