protected function getValidFromDate($fieldSource, $fieldName, $prevRoundId, \Gems_Tracker_Token $token, \Gems_Tracker_RespondentTrack $respTrack)
    {
        return $this->getValidUntilDate($fieldSource, $fieldName, $prevRoundId, $token, $respTrack, false);
    }
protected function getValidFromDate($fieldSource, $fieldName, $prevRoundId, \Gems_Tracker_Token $token, \Gems_Tracker_RespondentTrack $respTrack)
    {
        return $this->getValidUntilDate($fieldSource, $fieldName, $prevRoundId, $token, $respTrack, false);
    }
protected function getValidFromDate ( $ fieldSource , $ fieldName , $ prevRoundId , \ Gems_Tracker_Token $ token , \ Gems_Tracker_RespondentTrack $ respTrack ) { return $ this -> getValidUntilDate ( $ fieldSource , $ fieldName , $ prevRoundId , $ token , $ respTrack , false ) ; }
Returns the date to use to calculate the ValidFrom if any

@param string $fieldSource Source for field from round
@param string $fieldName Name from round
@param int $prevRoundId Id from round
@param \Gems_Tracker_Token $token
@param \Gems_Tracker_RespondentTrack $respTrack
@return \MUtil_Date date time or null
Returns the date to use to calculate the ValidFrom if any