docs: protected StmtCommonTableScanShared defineCommonTableScanShared(String tableName, int stmtId) {
          assert (m_commonTableSharedMap.get(tableName) == null);
          StmtCommonTableScanShared answer = new StmtCommonTableScanShared(tableName, stmtId);
          m_commonTableSharedMap.put(tableName, answer);
          return answer;
      }