code: private void deleteColumn(String storeName, String rowKey, String colName) {
          Map<String, List<String>> rowMap = m_columnDeletes.get(storeName);
          if (rowMap == null) {
              rowMap = new HashMap<>();
              m_columnDeletes.put(storeName, rowMap);
          }
          List<String> colNames = rowMap.get(rowKey);
          if (colNames == null) {
              colNames = new ArrayList<>();
              rowMap.put(rowKey, colNames);
          }
          colNames.add(colName);
          m_totalUpdates++;
      }
docs: Add the given column deletion.