`charset` for `<object-to-string-transformer>` was placed in the common `inputOutputChannelGroup` attributeGroup. `charset` wasn't available within `<chain>`. * Move 'charset' from `inputOutputChannelGroup` to the new `specialized-transformer-charset-aware-type` complexType * Add test for 'charset' within `<chain>` JIRA: https://jira.springsource.org/browse/INT-2958