Fix swagger errors (#4220)

Fix all the resting errors to have a valid swagger file.

They are still some warnings but nothing blocking.

Doing so I found that some request still misses son parameters for some POST/PUT/PATCH request. This means the a client generated from the swagger file will not work completely. 

Fix #4088 by activating validation in drone
Should fix #4010.

Author: sapk

.drone.yml

@@ -75,6 +75,7 @@ pipeline:
       - make lint
       - make fmt-check
       - make swagger-check
+      - make swagger-validate
       - make misspell-check
       - make test-vendor
       - make build