STATIC_IP_CHECKERS are used for uptime checks that perform egress
across the public internet. STATIC_IP_CHECKERS use the static IP
addresses returned by ListUptimeCheckIps.
Unspecified
The default checker type. Currently converted to STATIC_IP_CHECKERS
on creation, the default conversion behavior may change in the future.
VpcCheckers
VPC_CHECKERS are used for uptime checks that perform egress using
Service Directory and private network access. When using VPC_CHECKERS,
the monitored resource type must be servicedirectory_service.