neutron-lib/api-ref/source/v2/samples/subnets/subnetpool-update-request.json

{
    "subnetpool": {
        "name": "my-new-subnetpool-name",
        "prefixes": [
            "2001:db8::/64",
            "2001:db8:0:1::/64",
            "2001:db8:0:2::/64"
        ],
        "min_prefixlen": 64,
        "default_prefixlen": 64,
        "max_prefixlen": 64
    }
}