Merge branch 'stable-3.2'

* stable-3.2:
  DeleteChangeUsingMultiGerrit1: Fix json change number
  Update events-broker to v3.2.0-rc4
  Fix NPE when migrating from v3.1.x to v3.2.0

Change-Id: I5768f84bd2d3de84a9059263d8d229e0bed3c7f0