//
// Query params:
//
//	user=... -> repeatable query parameter, specifying users to query for
//	policy mapping
//
//	group=... -> repeatable query parameter, specifying groups to query for
//	policy mapping
//
//	policy=... -> repeatable query parameter, specifying policy to query for
//	user/group mapping
//
// When all query parameters are omitted, returns mappings for all policies.