There's a second class of dependencies to be aware of: Implied dependencies. Basically, some plugins used to be core features (e.g. Subversion, or JUnit plugin). Other plugins that have been developed against versions of core old enough that those features were in core may or may not be using these (formerly core) features – so Jenkins treats them as if they do. So an older core version dependency can therefore mean a plugin picks up a number of implied dependencies. We should also display these, but in a separate list next to the regular guaranteed-to-be-used dependencies we already show.
This list maintained in code unfortunately, contains these "detached" (used to be in core and now are not) plugins, the version in which they were removed from core (i.e. 1.576 was the last core to contain junit features), and which version of the newly created plugin the implied dependency is on (usually 1.0 but not always)
Addressing comments in WEBSITE-327: Showing the 'reverse dependencies' for these makes no sense, as some plugins may have 1000+ reverse dependencies.