protected boolean putInternal(Data key, Data value) {
   throwExceptionIfNull(key);
   throwExceptionIfNull(value);
   Collection<MultiMapRecord> coll = txMap.get(key);
   long recordId = -1;
   long timeout = tx.getTimeoutMillis();
   long ttl = extendTimeout(timeout);
   final MultiMapTransactionLog log;
   if (coll == null) {
     MultiMapResponse response = lockAndGet(key, timeout, ttl);
     if (response == null) {
       throw new ConcurrentModificationException(
           "Transaction couldn't obtain lock " + getThreadId());
     }
     recordId = response.getNextRecordId();
     coll = createCollection(response.getRecordCollection(getNodeEngine()));
     txMap.put(key, coll);
     log = new MultiMapTransactionLog(key, name, ttl, getThreadId());
     tx.addTransactionLog(log);
   } else {
     log = (MultiMapTransactionLog) tx.getTransactionLog(getTxLogKey(key));
   }
   MultiMapRecord record =
       new MultiMapRecord(config.isBinary() ? value : getNodeEngine().toObject(value));
   if (coll.add(record)) {
     if (recordId == -1) {
       recordId = nextId(key);
     }
     record.setRecordId(recordId);
     TxnPutOperation operation = new TxnPutOperation(name, key, value, recordId);
     log.addOperation(operation);
     return true;
   }
   return false;
 }
 protected boolean removeInternal(Data key, Data value) {
   throwExceptionIfNull(key);
   throwExceptionIfNull(value);
   Collection<MultiMapRecord> coll = txMap.get(key);
   long timeout = tx.getTimeoutMillis();
   long ttl = extendTimeout(timeout);
   final MultiMapTransactionLog log;
   if (coll == null) {
     MultiMapResponse response = lockAndGet(key, timeout, ttl);
     if (response == null) {
       throw new ConcurrentModificationException(
           "Transaction couldn't obtain lock " + getThreadId());
     }
     coll = createCollection(response.getRecordCollection(getNodeEngine()));
     txMap.put(key, coll);
     log = new MultiMapTransactionLog(key, name, ttl, getThreadId());
     tx.addTransactionLog(log);
   } else {
     log = (MultiMapTransactionLog) tx.getTransactionLog(getTxLogKey(key));
   }
   MultiMapRecord record =
       new MultiMapRecord(config.isBinary() ? value : getNodeEngine().toObject(value));
   Iterator<MultiMapRecord> iterator = coll.iterator();
   long recordId = -1;
   while (iterator.hasNext()) {
     MultiMapRecord r = iterator.next();
     if (r.equals(record)) {
       iterator.remove();
       recordId = r.getRecordId();
       break;
     }
   }
   if (recordId != -1) {
     TxnRemoveOperation operation = new TxnRemoveOperation(name, key, recordId, value);
     log.addOperation(operation);
     return recordId != -1;
   }
   return false;
 }