Make ObjectDownloadListener public

The same was already done for ObjectUploadListener in I5b0fb1220.

Change-Id: Ie8a79f715fe69bed9331962fb478f7e35acf8680
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

org.eclipse.jgit.lfs.server/src/org/eclipse/jgit/lfs/server/fs/ObjectDownloadListener.java

@@ -61,9 +61,11 @@ import org.eclipse.jgit.lfs.lib.Constants;
 import org.eclipse.jgit.util.HttpSupport;
 
 /**
- * Handle asynchronous large object download
+ * Handle asynchronous large object download.
+ *
+ * @since 4.7
  */
-class ObjectDownloadListener implements WriteListener {
+public class ObjectDownloadListener implements WriteListener {
 
 	private static Logger LOG = Logger
 			.getLogger(ObjectDownloadListener.class.getName());