For all EX and QFX switches supported in Mist.
https://www.mist.com/documentation/static-routes/
GET API /v1/sites/:site_id/devices/:device_id/config_cmd to see intended switch config
"set groups top routing-options static route 10.2.4.0/24 next-hop [ 172.4.5.6 ]",
"set groups top routing-options static route 192.168.0.0/16 next-hop [ 20.4.5.6 ]",