* stable-2.15:
ListChangesOption: Add missing word in Javadoc
Update git submodules
AccountIT#updateDisplayName: Rewrite to work with updated account manager
AccountApiImpl: Fix message in exception
RelatedChangeAndCommitInfo: Use default CommitInfo#toString
Support Get Related in extension API
CommitInfo: Use ToStringHelper
CommitInfo: Handle root commits in toString()
Implement equals/hashCode/toString in CommitInfo and friends
Set version to 2.15.9-SNAPSHOT
AccountIT: Disable failing updateDisplayName test
Change-Id: Id2c1ad86a3f5ebb62a932b02d315330ae7a11102
f4b7be549a