Metadata auth

could you please take a look at this one, its for this change
http://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-authentication.html

example
https://s3.amazonaws.com/cloudformation-templates-us-east-1/S3Bucket_SourceAuth.template

I'm not sure its the best approach tough so if you can share your comments I'm willing to help with this one its blocking us cause we are using this option so I'm currently using this

I don't know openstack, do you know if openstack's version of cloudformation allows the AuthenticationBlock property?