The GLU process for unmarshaling XML involves converting the XML data into JSON format, followed by the unmarshaling of the JSON. If the connector request calls for XML, the JSON data is then converted back to XML.
Example payload to UnMarshall

You can copy the XML body into a JSON Converter to make it more readable:
Code Beautify

GLU needs to be told where the parameters are, so you need to read into the XML body for the parameter location.
Examples
First define the parameter name.

offlineMode is a simple parameter- it’s path is
soap:Envelope.soap:Body.ns1:datadictionaryResponse.return
In the Unmarshalling section the name of the attribute to unmashall from is defined in attributes name with the unmarshall coming from the Body.

In the Object / Collection Path you would define the path to get to the attribute, which would be
soap:Envelope.soap:Body.ns1:datadictionaryResponse.return