Values:
TARGET_UNSPECIFIED (0):
Target not specified.
PEERING_VPC (1):
Forwarded to a VPC peering network.
VPN_GATEWAY (2):
Forwarded to a Cloud VPN gateway.
INTERCONNECT (3):
Forwarded to a Cloud Interconnect connection.
GKE_MASTER (4):
Forwarded to a Google Kubernetes Engine
Container cluster master.
IMPORTED_CUSTOM_ROUTE_NEXT_HOP (5):
Forwarded to the next hop of a custom route
imported from a peering VPC.
CLOUD_SQL_INSTANCE (6):
Forwarded to a Cloud SQL instance.
ANOTHER_PROJECT (7):
Forwarded to a VPC network in another
project.
NCC_HUB (8):
Forwarded to an NCC Hub.
ROUTER_APPLIANCE (9):
Forwarded to a router appliance.
