code: RowIterator findFkRef(Session session, Object[] row, boolean delete) {
  
          if (row == null || ArrayUtil.hasNull(row, core.mainCols)) {
              return core.refIndex.emptyIterator();
          }
  
          PersistentStore store = session.sessionData.getRowStore(core.refTable);
  
          return core.refIndex.findFirstRow(session, store, row, core.mainCols);
      }
docs: New method to find any referencing row for a foreign key (finds row in
  child table). If ON DELETE CASCADE is specified for this constraint, then
  the method finds the first row among the rows of the table ordered by the
  index and doesn't throw. Without ON DELETE CASCADE, the method attempts
  to finds any row that exists. If no
  row is found, null is returned. (fredt@users)
  
  @param session Session
  @param row array of objects for a database row
  @param delete should we allow 'ON DELETE CASCADE' or 'ON UPDATE CASCADE'
  @return iterator
  @