Update doc on getConfiguredNetworks

BUg: 7223590
Change-Id: Id92699ae48ea75f94638fcc3bd776b863911985b

Author: isheriff

wifi/java/android/net/wifi/WifiManager.java

@@ -540,7 +540,8 @@ public WifiManager(Context context, IWifiManager service) {
      * <li>allowedGroupCiphers</li>
      * </ul>
      * @return a list of network configurations in the form of a list
-     * of {@link WifiConfiguration} objects.
+     * of {@link WifiConfiguration} objects. Upon failure to fetch or
+     * when when Wi-Fi is turned off, it can be null.
      */
     public List<WifiConfiguration> getConfiguredNetworks() {
         try {