code: @Implementation
    protected int updateNetwork(WifiConfiguration config) {
      if (config == null || config.networkId < 0 || readOnlyNetworkIds.get(config.networkId)) {
        return -1;
      }
      networkIdToConfiguredNetworks.put(config.networkId, makeCopy(config, config.networkId));
      return config.networkId;
    }
docs: Adds or updates a network which can later be retrieved with {@link #getWifiConfiguration(int)}
  method. A null {@param config}, or one with a networkId less than 0, or a networkId that had
  its updatePermission removed using the {@link #setUpdateNetworkPermission(int, boolean)} will
  return -1, which indicates a failure to update.