code: public synchronized void setMembers(String[] urls) {
  		HashMap<String,RangeMember> newMembers = 
  			new HashMap<String,RangeMember>();
  		
  		for(int i=0; i < urls.length; i++) {
  			if(members.containsKey(urls[i])) {
  				newMembers.put(urls[i],members.get(urls[i]));
  			} else {
  				RangeMember newMember = new RangeMember();
  				newMember.setUrlBase(urls[i]);
  				newMembers.put(urls[i],newMember);
  			}
  		}
  		members = newMembers;
  	}
docs: Update the list of members of this group. Members that disappear are
  lost, but members that remain across the operation retain their state.
  @param urls