#vulnerable code 
                                @Override
    public boolean hasNext()
    {
        return currentIteratorHasNext() || possibleChunksRemaining();
    } 
                            #location 4 
                            #vulnerability type THREAD_SAFETY_VIOLATION
#fixed code
                                @Override
    public boolean hasNext()
    {
        if(currentIteratorHasNext())
        {
            return true;
        }

        loadNextChunkIterator();

        return currentIteratorHasNext();
    }