Validate advertising id for zero value (#479)

Author: hborisoff

AndroidSDKCore/src/main/java/com/leanplum/internal/Constants.java

@@ -43,6 +43,7 @@ public class Constants {
   public static final String LEANPLUM_PACKAGE_IDENTIFIER = BuildConfig.LEANPLUM_PACKAGE_IDENTIFIER;
   static final String INVALID_MAC_ADDRESS = "02:00:00:00:00:00";
   static final String INVALID_MAC_ADDRESS_HASH = "0f607264fc6318a92b9e13c65db7cd3c";
+  static final String INVALID_UUID = "00000000-0000-0000-0000-000000000000";
 
   /**
    * From very old versions of the SDK, leading zeros were stripped from the mac address.

AndroidSDKCore/src/main/java/com/leanplum/internal/Util.java

@@ -258,6 +258,10 @@ public static boolean isValidUserId(String userId) {
       Log.d(logPrefix + "(sentinel): " + userId);
       return false;
     }
+    if (Constants.INVALID_UUID.equals(userId)) {
+      Log.d(logPrefix + "(zero uuid): " + userId);
+      return false;
+    }
     if (userId.length() > Constants.MAX_USER_ID_LENGTH) {
       Log.d(logPrefix + "(too long): " + userId);
       return false;
@@ -278,7 +282,8 @@ public static boolean isValidDeviceId(String deviceId) {
     if (deviceId == null || deviceId.isEmpty() ||
         Constants.INVALID_ANDROID_ID.equals(deviceId) ||
         Constants.INVALID_MAC_ADDRESS_HASH.equals(deviceId) ||
-        Constants.OLD_INVALID_MAC_ADDRESS_HASH.equals(deviceId)) {
+        Constants.OLD_INVALID_MAC_ADDRESS_HASH.equals(deviceId) ||
+        Constants.INVALID_UUID.equals(deviceId)) {
       Log.d(logPrefix + "(sentinel): " + deviceId);
       return false;
     }