code: public Object setAttribute(String name, Object obj)
    {
      if (obj == null) {
        if (_attributes == null)
          return null;
        else
          return _attributes.remove(name);
      }
  
      if (_attributes == null)
        _attributes = new ConcurrentHashMap<String,Object>(8);
  
      return _attributes.put(name, obj);
    }
docs: Sets the named attributes