modify apiSettings url

We are setting up wordpress page, using contactform7 plugin. In front of wordpress, we will have a transparent proxy set up (Apache).
We would need to change URL set up in apiSettings, as proxy has problems rewriting url to local (proxy) url.

How can we set URL to relative, so it will be working?

For example:

<script type=’text/javascript’>
/* <![CDATA[ */
var wpcf7 = {“apiSettings”:{“root”:”\/wp-json\/contact-form-7\/v1″,”namespace”:”contact-form-7\/v1″},”recaptcha”:{“messages”:{“empty”:”Bitte best\u00e4tige, dass du keine Maschine bist.”}}};
/* ]]> */
</script>