Started implementation of ClosingStructuresCalculationConfigurationImporter Moved some shared methods into extension classes. Related to Issue [WTI-1170]git-svn-id: https://repos.deltares.nl/repos/WettelijkToetsInstrumentarium/trunk@9140 5a3db67b-de53-47b5-99c8-a1c30a6650e2Former-commit-id: 21306f1a5f79ed47e062310ed4d7187b9402f36dFormer-commit-id: 726c1c58829e37df69debc7b728cdc57fcca2531