Update notes for submitted changes

* ObjectWalk: Add null check before skip tree.

7b/a261fb5f516dce83adc6f3bd4ac1666a51193e

@@ -0,0 +1,8 @@
+Verified+1: JGit Bot <jgit-bot@eclipse.org>
+Code-Review+2: Jonathan Nieder <jrn@google.com>
+Code-Review+1: Minh Thai <mthai@google.com>
+Submitted-by: Jonathan Nieder <jrn@google.com>
+Submitted-at: Mon, 02 Mar 2020 13:37:59 -0500
+Reviewed-on: https://git.eclipse.org/r/158371
+Project: jgit/jgit
+Branch: refs/heads/master