public String key() {
            StringBuilder buf = new StringBuilder();
            buf.append("t=").append(serviceType);
            buf.append(" cfg=").append(configId);
            buf.append(" suf=").append(portSuffix);
            return buf.toString();
        }
Models an immutable list of network port allocations

@author arnej
config-provisioning/src/main/java/com/yahoo/config/provision/NetworkPorts.java