failoverPolicy property
Requires at least one backend instance group to be defined as a backup (failover) backend. For load balancers that have configurable failover: [Internal passthrough Network Load Balancers](https://cloud.google.com/load-balancing/docs/internal/failover-overview) and [external passthrough Network Load Balancers](https://cloud.google.com/load-balancing/docs/network/networklb-failover-overview).
failoverPolicy cannot be specified with haPolicy.
Implementation
BackendServiceFailoverPolicy? failoverPolicy;