Can’t generate roave/security-advisories audit in json format

I am trying to generate a sample output via composer update --dry-run roave/security-advisories --audit-format json as I need to know what the JSON structure looks like. Unfortunately, I can’t get it to install packages that have security vulnerabilities, since roave/security-advisories has packages with security vulnerabilities in its conflicts script.
Unfortunately I also can’t find any documentation regarding the JSON structure.
Does anyone here have an example output that they could provide me with or a reference where I can read about it?