code: public synchronized void setAttribute(String key, Boolean value)
  	{
  		if(attributes.containsKey(key))
  		{
  			attributes.remove(key);
  		}
  		attributes.put(key, value);
  	}
docs: /* (non-Javadoc)
  @see org.overture.ide.internal.core.resources.IOptionGroup#setAttribute(java.lang.String, boolean)