docs: private Map<StaticBuffer, Pair<Put, Delete>> convertToCommands(Map<String, Map<StaticBuffer, KCVMutation>> mutations,
                                                                     final long putTimestamp,
                                                                     final long delTimestamp) throws PermanentBackendException {
          Map<StaticBuffer, Pair<Put, Delete>> commandsPerKey = new HashMap<StaticBuffer, Pair<Put, Delete>>();
  
          for (Map.Entry<String, Map<StaticBuffer, KCVMutation>> entry : mutations.entrySet()) {
  
              String cfString = getCfNameForStoreName(entry.getKey());
              byte[] cfName = cfString.getBytes();
  
              for (Map.Entry<StaticBuffer, KCVMutation> m : entry.getValue().entrySet()) {
                  byte[] key = m.getKey().as(StaticBuffer.ARRAY_FACTORY);
                  KCVMutation mutation = m.getValue();
  
                  Pair<Put, Delete> commands = commandsPerKey.get(m.getKey());
  
                  if (commands == null) {
                      commands = new Pair<Put, Delete>();
                      commandsPerKey.put(m.getKey(), commands);
                  }
  
                  if (mutation.hasDeletions()) {
                      if (commands.getSecond() == null) {
                          Delete d = new Delete(key);
                          compat.setTimestamp(d, delTimestamp);
                          commands.setSecond(d);
                      }
  
                      for (StaticBuffer b : mutation.getDeletions()) {
                          commands.getSecond().deleteColumns(cfName, b.as(StaticBuffer.ARRAY_FACTORY), delTimestamp);
                      }
                  }
  
                  if (mutation.hasAdditions()) {
                      if (commands.getFirst() == null) {
                          Put p = new Put(key, putTimestamp);
                          commands.setFirst(p);
                      }
  
                      for (Entry e : mutation.getAdditions()) {
                          commands.getFirst().add(cfName,
                                  e.getColumnAs(StaticBuffer.ARRAY_FACTORY),
                                  putTimestamp,
                                  e.getValueAs(StaticBuffer.ARRAY_FACTORY));
                      }
                  }
              }
          }
  
          return commandsPerKey;
      }