Nameless JSON parameter in ASM

We're trying to parse JSON objects for parameters in our ASM policy. The content type is application/json. On one of our API endpoints, we receive payload that looks like this:

["sensitive data here"]

I believe this is technically valid JSON as a bare array. It seems that the ASM expects everything to be a key-value pair. How do I parse this payload into a parameter so that I can then mark that parameter for exclusion from logs?