Using the TransformData Class with JSON

Hi!

I'd like to employ a "Transform Only" App Engine to transform some data in the response message of the QAS_EXECUTEQRY_REST_GET service operation. Specifically, I want to transform any signed negative numeric values to have a leading zero. For example, the PSQuery returns -0.42, but the JSON in the response message contains -.42.

I know that I can use the TransformData class in my App Engine Peoplecode (e.g., TransformDataObject = %TransformData;). And the TransformData object has a property of XmlDoc. But we are returning JSON, not XML, so is there a way to accomplish this using the delivered class methods?