code: @Override
      public Object get(int key, Object defaultValue) {
  	if (key <= 0) return defaultValue;
  	if (key > list.size()) return defaultValue;
  
  	try {
  	    Object rtn = list.get(key - 1);
  	    if (rtn == null) {
  		if (NullSupportHelper.full()) {
  		    return null;
  		}
  		return defaultValue;
  	    }
  	    return rtn;
  	}
  	catch (Exception e) {
  	    return defaultValue;
  	}
      }
docs: /*---@Override
  public boolean containsKey(int index) {
  super.containsKey(index);
  return get(index-1,null)!=null;
  }