Merge "unregistered null callback will cause a crash later" am: f4e0f096b5 am: 645d524fba

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/2372391

Change-Id: I44beeb193041c47c3b98c3c1a10ecb195511dd97
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
diff --git a/Tethering/src/com/android/networkstack/tethering/Tethering.java b/Tethering/src/com/android/networkstack/tethering/Tethering.java
index b3ec805..e1b7016 100644
--- a/Tethering/src/com/android/networkstack/tethering/Tethering.java
+++ b/Tethering/src/com/android/networkstack/tethering/Tethering.java
@@ -2407,6 +2407,9 @@
 
     /** Unregister tethering event callback */
     void unregisterTetheringEventCallback(ITetheringEventCallback callback) {
+        if (callback == null) {
+            throw new NullPointerException();
+        }
         mHandler.post(() -> {
             mTetheringEventCallbacks.unregister(callback);
         });