Merge pull request #22 in ZP/z-push from feature/ZP-659-backendcombined-add-changessink-methods to develop

* commit '1af618fb':
  ZP-659 Remove else. Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-659 - Add ChangesSink methods. Released under the Affero GNU General Public License (AGPL) version 3.

(cherry picked from commit 5ef30764)