Messaging: Fix modifiers

We either have too few or too many

Change-Id: I09a9a38b859c68526fcbcdbc7862afe1d693f6c0

src/com/android/messaging/sms/SmsSender.java

@@ -60,7 +60,7 @@ public class SmsSender {
     /*
      * A map for pending sms messages. The key is the random request UUID.
      */
-    private static ConcurrentHashMap<Uri, SendResult> sPendingMessageMap =
+    private static final ConcurrentHashMap<Uri, SendResult> sPendingMessageMap =
             new ConcurrentHashMap<Uri, SendResult>();
 
     private static final Random RANDOM = new Random();