UpdateSite in Jenkins can return null from getConnectionCheckUrl() in order to indicate that the connection check should be skipped.

In Jenkins 2.2 there is no special status for the "SKIPPED" connection check. UpdateCenter::doCheckConnection() returns

in such case.

When PluginSetupWizard.js::checkConnectivity() receives such UNCHECKED result, it tries to query Jenkins again with 100ms timeout. Actually it leads to the infinite loop, because Jenkins UpdateCenter returns "UNCHECKED" forever.