code: public OvhFailoverIp project_serviceName_ip_failover_id_attach_POST(String serviceName, String id, String instanceId) throws IOException {
  		String qPath = "/cloud/project/{serviceName}/ip/failover/{id}/attach";
  		StringBuilder sb = path(qPath, serviceName, id);
  		HashMap<String, Object>o = new HashMap<String, Object>();
  		addBody(o, "instanceId", instanceId);
  		String resp = exec(qPath, "POST", sb.toString(), o);
  		return convertTo(resp, OvhFailoverIp.class);
  	}
docs: Attach failover ip to an instance
  
  REST: POST /cloud/project/{serviceName}/ip/failover/{id}/attach
  @param id [required] Ip id
  @param instanceId [required] Attach failover ip to instance
  @param serviceName [required] Project id