Can rule criteria have references to items in a JSON array?

For example, within a rule, I have a criteria that looks like this:

criteria:
  trigger.body.refChanges[0].type:
    type: "nequals"
    pattern: "DELETE"

What bothers me is that the criteria references the first element of a JSON array.

Is this a “legal” rule criteria?

I just tested this using st2-rule-tester. The above syntax works.