Set User Properties
Set custom properties on users who have previously been identified in the browser via the FS.identify Browser API function.
System fields and custom field types
This API will only work for previously-identified users for whom the FS.identify or FS.setUserVars Browser API was called. Anonymous users lack the required
uid necessary for this API to function.
Optional explicit integration field for integrations to mark their events.
Request Body required
A successful response.