D10829: Use DocumentId class

[Michael Heidelbach]

michaelh planned changes to this revision.

REPOSITORY
  R293 Baloo

REVISION DETAIL
  https://phabricator.kde.org/D10829

To: michaelh, adridg, #baloo, #frameworks
Cc: alexeymin, ashaposhnikov, michaelh, spoorun, nicolasfella