In my case I wanted to count the number of elements inside an XML that was a result I got back from a SAP query. Below a small example.

Inside the Set Properties shape you specify a Dynamic Document Process like this

In the Groovy script we set that attribute according to the full path of the dynamic process property which must be prefixed with document.dynamic.userdefined

document.dynamic.userdefined.rowcount

e.g.

When you later on try to access the Dynamic Document Property you need to just use the last part again, in my example “rowcount”