question: private void initialize ( Collection < OrganisationUnit > sources , Collection < Period > periods , Collection < ValidationRule > rules ) { addPeriodsToContext ( periods ) ; boolean surveillanceRulesPresent = addRulesToContext ( rules ) ; removeAnyUnneededPeriodTypes ( ) ; addSourcesToContext ( sources , true ) ; countOfSourcesToValidate = sources . size ( ) ; if ( surveillanceRulesPresent ) { Set < OrganisationUnit > otherDescendants = getAllOtherDescendants ( sources ) ; addSourcesToContext ( otherDescendants , false ) ; } }
target:  Initializes context values based on sources, periods and rules