preferred_handler
Description:
Either the well-known bus name (starting with 
        CLIENT_BUS_NAME_BASE) of the preferred handler for this channel request, or null to indicate that any handler would be
      acceptable.
Read-only.
Either the well-known bus name (starting with 
        CLIENT_BUS_NAME_BASE) of the preferred handler for this channel request, or null to indicate that any handler would be
      acceptable.
Read-only.