code: public Map<String, List<String>> getRowDeletesMap() {
          Map<String, List<String>> storeMap = new HashMap<>();
          for(RowDelete mutation: getRowDeletes()) {
              String storeName = mutation.getStoreName();
              String rowKey = mutation.getRowKey();
              List<String> rowList = storeMap.get(storeName);
              if(rowList == null) {
                  rowList = new ArrayList<>();
                  storeMap.put(storeName, rowList);
              }
              rowList.add(rowKey);
          }
          return storeMap;
      }
docs: Get the map of the row deletes as storeName -> list of row keys