Implied dependencies can be uninstalled, but they will forcibly be restored on startup (if bundled).

So allowing them to be uninstalled is pointless.

Steps to reproduce

1. Install Caffeine API on 2.365.
2. Get JavaBeans Activation Framework (JAF) API, JavaMail API, bouncycastle API, Instance Identity additionally.
3. Uninstall as many of them (but not Caffeine API) as possible.
4. Restart

Expected Results

Plugins remain uninstalled

Actual Results

2022-08-31 09:09:53.606+0000 [id=35]    INFO    hudson.PluginManager#considerDetachedPlugin: Loading a detached plugin as a dependency: /var/jenkins_home/plugins/javax-mail-api.jpi
2022-08-31 09:09:53.667+0000 [id=35]    INFO    hudson.PluginManager#considerDetachedPlugin: Loading a detached plugin as a dependency: /var/jenkins_home/plugins/bouncycastle-api.jpi
2022-08-31 09:09:53.733+0000 [id=35]    INFO    hudson.PluginManager#considerDetachedPlugin: Loading a detached plugin as a dependency: /var/jenkins_home/plugins/instance-identity.jpi 

Notes

They remain disabled if they've been disabled before uninstallation, kind of defeating the purpose of forced installation, as JENKINS-68194 points out.

Suggestions

• (Preferred) Allow uninstallation, but add a marker file that prevents re-installation unless it's a mandatory dependency.
• Disallow uninstallation.