It's simply a template method that abstracts common functionality in the two new concrete classes AnyAuthenticationManager and AllAuthenticationManager. In practice AnyAuthenticationManager#isSatisfied(...) returns true if successes.size() > 0 and AllAuthenticationManager returns true if credentials.size() == successes.size(). The other method parameters are available for more interesting policies, but I don't have a use case or even a hypothetical case at the moment.