Trying to retrieve the "D-Bus Introspection XML file" with this command:

  dbus-send --session \
            --dest=org._01.pim.contacts \
            --print-reply=literal \
            /org/01/pim/contacts \
            org.freedesktop.DBus.Introspectable.Introspect

I noticed that some of the functions seems incomplete
(some return values are not shown as expected):

1)   GetSortOrder
     <method name="GetSortOrder"/>
Should be
     <method name="GetSortOrder">                                         
          <arg type="s" direction="out"/>
     </method>

2)   GetAllPeers
     <method name="GetAllPeers"/>
Should be (I think)
     <method name="GetAllPeers">
          <arg type="as" direction="out"/>
     </method>

3)   Search
The return object seems missing.