Use of route_tables.begin_create_or_update yields removal of all routes and adds new entry

[erniedavisAA]

using the sdk for creating vnets and subnets in azure, and when adding a new route table entry, the new route table entry removed all existsing routes and added the new route to the route table.

The expected behavior would be to add another entry to the route table, rather than replace the route table contents with a single entry.

here is the sample code...

        routeTableResponse = network_client.route_tables.begin_create_or_update(
        resource_group_name=rgname,
        route_table_name=rtname,
        parameters={
          "location": region,
          "properties": {
            "disableBgpRoutePropagation": False, 
            "routes": [
              {
                "name": newvnetname,
                "properties": { 
                    "addressPrefix": newvnetprefix, 
                    "nextHopType": "VirtualAppliance", 
                    "nextHopIpAddress": hublbipaddress} 
              }
            ],
          }
        }
    ).result()