What is the JSON query syntax and where is it documented?

The query syntax looks somewhat like jq but it seems to be different.

For example `cat json | jq 'select(.event == "foo").value'` would yield all the values for objects where "event" == "foo", but this syntax does not seem to work with this plugin.

I have also seen `$.[?(@.event=="foo")].value`, but this does not seem to work either.