There's a bug in the ToDataSerializer which loses track of the current path, so we get repeated elements in the warning message:
['resources']['Yaml_settings[cassandra::config]']['parameters']['values']['system_value'][0] contains a hash with an Array key. It will be converted to the String '["listen_address"]'
['resources']['Yaml_settings[cassandra::config]']['parameters']['values']['system_value'][0]['resources']['Yaml_settings[cassandra::config]']['parameters']['values']['system_value'][0] contains a hash with an Array key. It will be converted to the String '["broadcast_rpc_address"]'