While working through some examples and testing I discovered that the JSON schema used in the xml-to-json example is missing the approvalCode field. It exists in the transformation.xml and the model, so I'm guessing it was added later somehow.
Here's the sample output message, which includes the field: https://github.com/fusesource/fuseide/blob/master/examples/transformation/xml-to-json/src/data/xyz-order.json
And here's the JSON schema file, which doesn't include the field: https://github.com/fusesource/fuseide/blob/master/examples/transformation/xml-to-json/src/main/resources/xyz-order-schema.json
We just need to add this to the schema file and all will be good again: