Indicate the NsdServiceInfo attributes are only filled in for a resolved service.

Fixes: 28530428

(cherry picked from commit 7d5da4b044183826ac8388c8bdb94ac979a81797)

Change-Id: If2bfc06589adb361f11b89cd5923cb5c255cb680
diff --git a/core/java/android/net/nsd/NsdServiceInfo.java b/core/java/android/net/nsd/NsdServiceInfo.java
index 4a06fb1..7b845be 100644
--- a/core/java/android/net/nsd/NsdServiceInfo.java
+++ b/core/java/android/net/nsd/NsdServiceInfo.java
@@ -250,7 +250,8 @@
     }
 
     /**
-     * Retrive attributes as a map of String keys to byte[] values.
+     * Retrieve attributes as a map of String keys to byte[] values. The attributes map is only
+     * valid for a resolved service.
      *
      * <p> The returned map is unmodifiable; changes must be made through {@link #setAttribute} and
      * {@link #removeAttribute}.