The DSS Setting mentioned on the commuinty page did not exist and therefore I created it myself. I don't know if that matters what so ever? I noticed that the decision tables mentioned do not appear in the trace (while having the correct trace settings of course). Hence my doubt about the DSS setting.
Thanks for your reply. I added additional context to this post, including:
the Pega log file, in which also the same error is mentioned.
config of the JSON response in the GET method of the REST connector.
response of the connector itself, providing the correct outcome when testing the connection (including the __metdata property, please see attachment).
the metadata property in the int class with external qualifier pxExternalName with value "__metadata" which I tried based on a tip I received. However unfortunately with the same outcome.
the DSS setting as mentioned in my first post.
Looking closely it appeared to be a dubble underscore ("__") in front of __metadata which is provided in the JSON reponse. I don't think the problem is secondary, as Pega does not recognize the underscore, what is also mentioned in the community page I shared.
The error message occurs when running the data page which is invoking the REST connector by the way.
Hopefully you have an idea how to solve this. If you need additional info then please let me know.
Thanks for preparing the materials. Now I understand your scenario.
You indeed have an element __metadata within your json response. I previously assumed that you were unaware of such element and were wondering where the error comes from.
The reason there is an issue mapping such element is that Pega does not allow to create properties starting with non-alphabetic characters. And the mode you chose for mapping implies automapping all elements including nested into properties with exactly same names. There is no such property (__metedata) in your data model (and cannot be, probably it is named in fact "Metadata" without underscores). The automapping would not work in such case.
Luckily there are other mapping options within connect-Rest rule. Use the option called map to Clipboard.
Select a Text property (e.g. create property named FullResponseJSON). The whole response in text format will be stored in mentioned property.
Then separately call an activity as the next step after your Connect-Rest rule is called and perform parsing of your FullResponseJSON.
In the activity you will need to call a JSON-type Datatransform. Create such rule and study it a little bit - it is very powerful - allows you to automap selectively and certain elements can be mapped to differently-named properties as required. Do not forget to pass a parameter DESERIALIZE to it (as you need it to map JSON to your class structure).
You can skip elements you do not need and __metadata can be mapped to property named Metadata. The nested elements can be even automapped.