In stable/train Cliff version is 2.16.0 which force us
to pin validations-libs or to handle backward compat directly
in the code.
For long term solution and to avoid tagging, pinning and complex
release management this review fix the compatibility with Cliff 2.16.0
Change-Id: I6dec4c154f088e8cc6450d5d9cf2f9b407fdefdc