diff --git a/core/java/android/app/NotificationChannelGroup.java b/core/java/android/app/NotificationChannelGroup.java
index 0fa3c7f..17c5cba 100644
--- a/core/java/android/app/NotificationChannelGroup.java
+++ b/core/java/android/app/NotificationChannelGroup.java
@@ -17,6 +17,7 @@
 
 import android.annotation.SystemApi;
 import android.annotation.TestApi;
+import android.annotation.UnsupportedAppUsage;
 import android.content.Intent;
 import android.os.Parcel;
 import android.os.Parcelable;
@@ -49,6 +50,7 @@
     private static final String ATT_ID = "id";
     private static final String ATT_BLOCKED = "blocked";
 
+    @UnsupportedAppUsage
     private final String mId;
     private CharSequence mName;
     private String mDescription;