Add @UnsupportedAppUsage annotations for greylist.

go/cleanup-greylist-txt

These have already been greylisted, however due to bugs/omissions in the tooling have been kept in go/greylist-txt instead of being annotated in the code.

This is partial merge of aosp/Id6c1f5e403a0e66edb1102ee45f3bf19f244fb09. Telephony greylist cleanup has been done separately. Note that annotations outside of frameworks/base/ have been merged from AOSP.

Bug: 137350495
Test: m
Exempt-From-Owner-Approval: merge
Change-Id: I015c466e8b69cc0fed5e9d394ba865aad11d8ba6
diff --git a/core/java/android/app/UserSwitchObserver.java b/core/java/android/app/UserSwitchObserver.java
index 25b243d..2f8ee744b 100644
--- a/core/java/android/app/UserSwitchObserver.java
+++ b/core/java/android/app/UserSwitchObserver.java
@@ -24,6 +24,11 @@
  * @hide
  */
 public class UserSwitchObserver extends IUserSwitchObserver.Stub {
+
+    @UnsupportedAppUsage
+    public UserSwitchObserver() {
+    }
+
     @Override
     public void onUserSwitching(int newUserId, IRemoteCallback reply) throws RemoteException {
         if (reply != null) {