Json to xml transformation

Using request transformer plugin I can change headers, body parameters and corresponding values. But I want to completely replace the body.
e.g. in the request I am passing json body {“key”:“value”} with application/json header. But my backend accepts xml, so I will change header to application/xml using Request Transformer plugin. But I cannot change that json body to xml. What I want to do is to pass completely new body content in xml format with different params and values.
Please suggest how can I achieve this.

Maybe you can use this plugin