Steps to reproduce:

1. Create a discovery item.
2. Choose key vmware.datastore.discovery.

Result:
Returns old JSON format.

{"data":[{"{#DATASTORE}":"FOO",...},{"{#DATASTORE}":"BAR",...}]}

Expected:
Return new JSON format.

[{"{#DATASTORE}":"FOO",...},{"{#DATASTORE}":"BAR",...}]

According to the documentation: "Built-in discovery keys have been updated to return an array of LLD rows at the root of JSON document."

Workaround for Preprocessing:

If you want to apply preprocessing, you have to catch this case so that you can access the elements as usual.