Add missing @since tags for new API

Change-Id: Iaf83f66637d6a13e4a6d096ba8529553af7e30ed
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

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

@@ -184,6 +184,7 @@ public class FileLfsServlet extends HttpServlet {
 	 *            error message
 	 * @throws IOException
 	 *             on failure to send the response
+	 * @since 4.6
 	 */
 	protected static void sendError(HttpServletResponse rsp, int status, String message)
 			throws IOException {

org.eclipse.jgit/src/org/eclipse/jgit/util/io/IsolatedOutputStream.java

@@ -71,6 +71,8 @@ import org.eclipse.jgit.internal.JGitText;
  * Every write (or flush) requires a context switch to another thread. Callers
  * should wrap this stream with {@code BufferedOutputStream} using a suitable
  * buffer size to amortize the cost of context switches.
+ *
+ * @since 4.6
  */
 public class IsolatedOutputStream extends OutputStream {
 	private final OutputStream dst;