I have a REST API Monitor configured for a very simple API endpoint in my system, but the monitor is reporting that my JSONPath expression is failing. The endpoint returns the following with Content-Type: application/json:

{"codeVersion":"1.0.0","apiVersion":"1.0.0"}

The monitor is configured for JSON response format and I've tried several different JSONPATH values:

1. $.apiVersion -- for this I got "JSON Path expression assertion "["$.apiVersion"]" has failed"
2. apiVersion -- for this I got "JSON Path expression assertion "["apiVersion"]" has failed"
3. [apiVersion] -- for this I got JSON Path expression assertion "["[apiVersion]"]" has failed

What am I doing wrong? Is there any documentation for supported JSONPath expressions?