The tooling generates this line in the switchyard.xml if you specify a Message Content Name:

<rules:implementation.rules messageContentName="test">

The problem is, messageContentName is MEANINGLESS to the rules component. It must have been a hitchhiker from the design of it's brother, the bpm component, where there is a optional message content name for both in and out.

To fix:
1) The option needs to get removed from the tooling.
2) The "messageContentName" attribute needs to get removed from components/rules/src/main/resources/org/switchyard/component/rules/config/model/v1/rules-v1.xsd.

No code inside components/rules/ has to change. Just the xsd.