text: public ExternalSheet getExternalSheet(int externSheetIndex) {String[] extNames = linkTable.getExternalBookAndSheetName(externSheetIndex);if (extNames == null) {return null;}if (extNames.length == 2) {return new ExternalSheet(extNames[0], extNames[1]);} else {return new ExternalSheetRange(extNames[0], extNames[1], extNames[2]);}}