[BUGFIX] Add missing method defined by the DataHandlerInterface

Change-Id: Icf0bc28dba083005625788dbd8085bae53f4472a
Reviewed-on: http://review.typo3.org/33200
Reviewed-by: Fabien Udriot <fabien.udriot@ecodev.ch>
Tested-by: Fabien Udriot <fabien.udriot@ecodev.ch>