Evaluate REST Connector Return Code

Hello, even after intensively searching I was not able to figure out how to evaluate the return code of a rest call. I do perform a REST POST to a SAP system, which returns different codes, like in the example. What is the correct way of evaluating this?

If this is not possible, I wonder how to work with the returned answer from SAP. I did notice that in case on an error, the response contains the text error. I understood from the documentation that we should be able to process the response through the Groovy script coded in the connector but I cannot make it read the answer. Surely it is a stupid oversight but I cannot make sense of the available field columns named Output and Variable Name. What goes where and how does a Groovy script look like that does process the response?