The org.freedesktop.DBus.Introspectable interface is implemented but not declared in the introspection data

[mvidner]

As @jreidinger reports:

While ruby-dbus services do implement the Introspectable interface, that interface is not included in its own introspection output:

$ RUBYLIB=lib ruby examples/service/service_newapi.rb &
$ busctl --user --list introspect org.ruby.service /org/ruby/MyInstance | grep -v '^\.'
NAME                            TYPE      SIGNATURE RESULT/VALUE FLAGS
org.freedesktop.DBus.Properties interface -         -            -
org.ruby.AnotherInterface       interface -         -            -
org.ruby.SampleInterface        interface -         -            -    

Compare with another service (well, the bus itself)

$ busctl --user --list introspect org.freedesktop.DBus /org/freedesktop/DBus | grep -v '^\.'
NAME                                 TYPE      SIGNATURE RESULT/VALUE FLAGS
org.freedesktop.DBus                 interface -         -            -
org.freedesktop.DBus.Debug.Stats     interface -         -            -
org.freedesktop.DBus.Introspectable  interface -         -            -
org.freedesktop.DBus.Monitoring      interface -         -            -
org.freedesktop.DBus.Peer            interface -         -            -
org.freedesktop.DBus.Properties      interface -         -            -

AFAIK this is not a regression, the library has always missed it.