[FIXED JENKINS-10530] regression: plugins were no longer identified as upstream snapshot dependencies

authentication error page doesn't have the user name field, and in any case there's no need to set it here, so skip it.

Functioning JDK installation after the Oracle site change. They now put binaries behind SSO, so we need a real HTML scraper to be able to get past this, hence the htmlunit dependency.

[FIXED JENKINS-10530] regression: plugins were no longer identified as upstream snapshot dependencies

Added base class for groovy view modularization

again.