@Override
    public String toString() {
        return "[" + diskGb.map(d -> "disk " + d + " Gb").orElse("") + "]";
    }
Overrides fields in a {@link com.yahoo.config.provision.Flavor}, e.g. when a flavor is not
tied to a specific disk.

@author freva
config-provisioning/src/main/java/com/yahoo/config/provision/host/FlavorOverrides.java