I am using the **latest** localstack docker image to test aws s3, lambda and cloudformation locally. s3 and lambda seems to be working fine but when I call cloudformation **create-stack** api it gives me a 502 BadGateway error. This is the command I am using

`aws cloudformation create-stack \
  --template-body template.yaml \
  --stack-name cfn-test \
  --parameters ParameterKey=BucketPrefix,ParameterValue=demo-bucket \
  --endpoint-url=http://localhost:4581`

This is the error I get:
`An error occurred (502) when calling the CreateStack operation (reached max retries: 4): Bad Gateway`

From docker logs I got the following error
`2019-12-31T22:12:09:ERROR:localstack.services.generic_proxy: Error forwarding request: 'str' object has no attribute 'get' Traceback (most recent call last):
  File "/opt/code/localstack/localstack/services/generic_proxy.py", line 242, in forward
    path=path, data=data, headers=forward_headers)
  File "/opt/code/localstack/localstack/services/cloudformation/cloudformation_listener.py", line 164, in forward_request
    modified_request = transform_template(req_data)
  File "/opt/code/localstack/localstack/services/cloudformation/cloudformation_listener.py", line 83, in transform_template
    if parsed.get('Transform') == 'AWS::Serverless-2016-10-31':
AttributeError: 'str' object has no attribute 'get'`

Although, when I try the **list-stacks** api it seems to be working fine
`aws --endpoint-url=http://localhost:4581 cloudformation list-stacks`

`{
    "StackSummaries": []
}`

`2019-12-31 22:10:51,865:API: 127.0.0.1 - - [31/Dec/2019 22:10:51] "GET / HTTP/1.1" 200 -`

I could not find a solution in any of the past issues or anywhere on the internet. Please assist
cloudformation = aws_stack.connect_to_resource('cloudformation')
        template = template_deployer.template_to_json(load_file(TEST_TEMPLATE_2))
        stack_name = 'stack-%s' % short_uid()
        cloudformation.create_stack(StackName=stack_name, TemplateBody=template)
        def check_stack():
            stack = get_stack_details(stack_name)
            self.assertEqual(stack['StackStatus'], 'CREATE_COMPLETE')
            return stack
        details = retry(check_stack, retries=3, sleep=2)
        stack_summaries = list_stack_resources(stack_name)
        queue_urls = get_queue_urls()
        topic_arns = get_topic_arns()
        stack_queues = [r for r in stack_summaries if r['ResourceType'] == 'AWS::SQS::Queue']
        for resource in stack_queues:
            self.assertIn(resource['PhysicalResourceId'], queue_urls)
        stack_topics = [r for r in stack_summaries if r['ResourceType'] == 'AWS::SNS::Topic']
        for resource in stack_topics:
            self.assertIn(resource['PhysicalResourceId'], topic_arns)
        
        outputs = details.get('Outputs', [])
        self.assertEqual(len(outputs), 1)
        self.assertEqual(outputs[0]['ExportName'], 'SQSQueue1-URL')
    def test_create_change_set(self):