Theme Manager Plugin
io.jenkins.plugins.thememanager.ThemeManagerFactory in theme-manager
Pluggable ability to add additional built-in themes. The descriptor's display name will be used for the UI label
Implementations:
Dark Theme Plugin: io.jenkins.plugins.darktheme.DarkThemeManagerFactory (view on GitHub)
Dark Theme Plugin: io.jenkins.plugins.darktheme.DarkThemeSystemManagerFactory (view on GitHub)
Theme Manager Plugin: io.jenkins.plugins.thememanager.none.NoOpThemeManagerFactory (view on GitHub)