message: Mark addNewKey with "CanIgnoreReturnValue".
  This API returns the key id of the newly added key, it can make sense to ignore it.
diff: @@ -173,6 +173,7 @@ public final class KeysetManager {
  * true immediately promotes it to primary. However, when you do keyset rotation, you almost
  * never want to make the new key primary, because old binaries don't know the new key yet.
  */
  + @CanIgnoreReturnValue
  @Deprecated
  public synchronized int addNewKey(
  com.google.crypto.tink.proto.KeyTemplate keyTemplate, boolean asPrimary)
  