Merge branch 'stable-2.9' into stable-2.10

* stable-2.9:
  Fix NPE when ReviewInput's message is empty
  Fix NPE in /projects/{name}/children?recursive when a parent is missing
  Fix NPE when submitting review with inline comments via REST

Conflicts:
	gerrit-server/src/main/java/com/google/gerrit/server/change/PostReview.java

Change-Id: Icfde6f0274f0ccc92773fd5a376e8c27099437ac