While creating a subnet user can specify a list of host-routes which specify a next-hop for different destination addresses. Code exists for it in neutron-spi and there is also attribute for it in neutron-subnet.yang, but this information is not stored in MDSAL.

Bug is in NeutronSubnetInterface.toMd() method where code to handle NeutronSubnet_HostRoutes is missing.

To reproduce:
1. If using devstack, use following to create subnet with host-route option:
neutron subnet-create --dns-nameserver 8.8.8.8 --host-route destination=1.1.1.0/24,nexthop=192.168.199.1 mynet1 192.168.199.0/24

2. If using postman/curl, use following json when creating subnet:
{
"subnet": {
"name": "",
"enable_dhcp": true,
"network_id": "e9330b1f-a2ef-4160-a991-169e56ab17f5",
"tenant_id": "4fd44f30292945e481c7b8a0c8908869",
"dns_nameservers": ["8.8.8.8"
],
"allocation_pools": [

{ "start": "192.168.199.2", "end": "192.168.199.254" }

],
"host_routes": [

{"nexthop": "192.168.199.1", "destination": "1.1.1.0/24"}

],
"ip_version": 4,
"gateway_ip": "192.168.199.1",
"cidr": "192.168.199.0/24",
"id": "3b80198d-4f7b-4f77-9ef5-774d54e17126"
}
}