[bug] Cloudcontrol on networkmanager core network with empty policy will hang

There seems to be a bug when you pass an empty policy to cloudcontrol to update your corenetwork in networkmanager. You can replicate this with the cli.

When you pass in a patch document of "[]" it immediately returns success, then when you query the request, it is stuck in pending. You can replicate this with cli:

aws cloudcontrol update-resource --type-name AWS::NetworkManager::CoreNetwork --identifier core-network-xxxxx --patch-document "[]"

{
    "ProgressEvent": {
        "TypeName": "AWS::NetworkManager::CoreNetwork",
        "Identifier": "core-network-xxxxx",
        "RequestToken": "23xxxxx07",
        "Operation": "UPDATE",
        "OperationStatus": "SUCCESS",
        ...
        

aws cloudcontrol get-resource-request-status --request-token 23xxxxx07

{
    "ProgressEvent": {
        "TypeName": "AWS::NetworkManager::CoreNetwork",
        "RequestToken": "23xxxxx07",
        "OperationStatus": "PENDING",
        "EventTime": "2022-09-07T16:39:46.821000+00:00"
    }
}

Its stuck in pending and did not resolve after days. There are no changes/updates reflected in network manager.

EDIT: looks like this issue occurs when "[]" is passed to NetworkManager::VpcAttachment