Add missing @NonNull annotation to AndroidKeyStoreProvider method.

Bug: 73959762
Test: none
Change-Id: I2298c8fe0893032f374629a5af128474ba0f679c
diff --git a/keystore/java/android/security/keystore/AndroidKeyStoreProvider.java b/keystore/java/android/security/keystore/AndroidKeyStoreProvider.java
index 1018926..2c45d43 100644
--- a/keystore/java/android/security/keystore/AndroidKeyStoreProvider.java
+++ b/keystore/java/android/security/keystore/AndroidKeyStoreProvider.java
@@ -339,6 +339,7 @@
         return new AndroidKeyStoreSecretKey(secretKeyAlias, uid, keyAlgorithmString);
     }
 
+    @NonNull
     public static AndroidKeyStoreKey loadAndroidKeyStoreKeyFromKeystore(
             @NonNull KeyStore keyStore, @NonNull String userKeyAlias, int uid)
             throws UnrecoverableKeyException  {