"Prepare Data Center app to comply with secure endpoint default" problem with compatibility with old Confluence and Jira versions by plugins

Hello, I’ve read that we need to add annotations described in https://developer.atlassian.com/platform/marketplace/dc-apps-platform-7-preparing-for-secure-endpoints/ to our plugins recourses because they can be enforced soon. My question is
when the enforcement will start and how plugin developers are expected to handle compatibility with older versions?