#vulnerable code 
                                @Override
    public void add(int index, T element) {
        internalIndexedAdd(index, element, true);
    } 
                            #location 3 
                            #vulnerability type THREAD_SAFETY_VIOLATION
#fixed code
                                @Override
    public void add(int index, T element) {
        internalIndexedAdd(index, element);
    }