static String toString(@Nullable Class<?> type, InetSocketAddress localAddress,
                           Set<SessionProtocol> protocols, long portGroup) {
        final StringBuilder buf = new StringBuilder();
        if (type != null) {
            buf.append(type.getSimpleName());
        }
        buf.append('(');
        buf.append(localAddress);
        buf.append(", ");
        buf.append(protocols);
        if (portGroup != 0) {
            buf.append(", group: ").append(portGroup);
        }
        buf.append(')');

        return buf.toString();
    }
Returns the port group this {@link ServerPort} belongs to, or {@code 0} if this {@link ServerPort}
doesn't belong to any port group.
core/src/main/java/com/linecorp/armeria/server/ServerPort.java