During development in Studio ( steps exactly as in task https://jira.ez.no/browse/EZS-793 ), on clear database we create draft from existing content "Why we love NYC" and after "Confirm" we don't see all versions of content. We should see 2 versions (Publish and Draft), but we see only Publish version.
It is causes because after click on Confirm, are running 3 endpoints :

1) Request URL:http://ezstudio.dev.local/api/ezp/v2/content/objects/68
Request Method:GET
In this method is cacheable in Http and in persistance.

2) ttp://ezstudio.dev.local/api/ezp/v2/content/objects/68/currentversion
Request Method:POST
In this method is not cacheable.

3) http://ezstudio.dev.local/api/ezp/v2/content/objects/68/versions
Request Method:GET
In this method is not cacheable in persistance, but controller return list from http cache

In file eZ/Publish/Core/REST/Server/Controller/Content.php we modified method loadContentVersions and it helps :

    public function loadContentVersions($contentId, Request $request)
    {
        $contentInfo = $this->repository->getContentService()->loadContentInfo($contentId);

        return new Values\VersionList(
            $this->repository->getContentService()->loadVersions($contentInfo),
            $request->getPathInfo()
        );
    }