code: public String login(String token, Authentication authentication) {
  		if (null == token) {
  			return login(authentication);
  		}
  		tokens.put(token, new TokenContainer(authentication));
  		return token;
  	}
docs: Login for a specific authentication, creating a specific token if given.
  
  @param token token to use
  @param authentication authentication to assign to token
  @return token