MAP: Handle MessageListing empty folder name if set to current path.

Check if destination folder is already setpath while processing
GetMessageListing Request for empty folderName.

Change-Id: I4ecd87264140fd347c71b428e3c4dffec3f91d48
diff --git a/src/com/android/bluetooth/map/BluetoothMapObexServer.java b/src/com/android/bluetooth/map/BluetoothMapObexServer.java
index a876740..4105b27 100644
--- a/src/com/android/bluetooth/map/BluetoothMapObexServer.java
+++ b/src/com/android/bluetooth/map/BluetoothMapObexServer.java
@@ -450,7 +450,7 @@
         HeaderSet replyHeaders = new HeaderSet();
         BluetoothMapAppParams outAppParams = new BluetoothMapAppParams();
         BluetoothMapMessageListing outList;
-        if(folderName == null) {
+        if(folderName == null || folderName.length() == 0 ) {
             folderName = mCurrentFolder.getName();
         }
         if(appParams == null){