Merge branch 'stable-3.0'

* stable-3.0:
  ReadOnlyByHttpIT: Extend to cover both 'readonly' and 'readonly~readonly'
  ReadOnlyByHttpIT: Extend assertions on response content
  ReadOnly: Format with google-java-format
  Allow endpoint "config/server/readonly"
  REST: Report state from PUT and DELETE

Change-Id: I0fbe2e131e646a2a6c8051d8fc699af53e9ee40b