* stable-3.2:
Update git submodules
Fix documentation of `container.slave`
Fix documentation of `container.slave`
Update git submodules
Update git submodules
Submit: Use updated change for response
Remove Content-Type header from 'Submit Revision' example
Update git submodules
Add support for Elasticsearch version 7.8.*
Fix `parent` in `gr-change-metadata` when there is no revision
Change-Id: Ifaaad90a7343da4e301137616bc7c82e92bd6f3c