public NodeResources unusedCapacityOf(Node host) {
        return availableCapacityOf(host, false, false);
    }
Calculate the unused capacity of given host.

Note that unlike {@link #availableCapacityOf(Node)}, this only considers resources and returns any unused
capacity even if the host does not have available IP addresses.

@param host the host to find free capacity of
@return a default (empty) capacity if not host, otherwise the free capacity
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/provisioning/HostCapacity.java