code: func (s *Server) getCachedAuthMethodValidator(name string) (uint64, authmethod.Validator, bool) {
  	s.aclAuthMethodValidatorLock.RLock()
  	defer s.aclAuthMethodValidatorLock.RUnlock()
  
  	if s.aclAuthMethodValidators != nil {
  		v, ok := s.aclAuthMethodValidators[name]
  		if ok {
  			return v.ModifyIndex, v.Validator, true
  		}
  	}
  	return 0, nil, false
  }
docs: // getCachedAuthMethodValidator returns an AuthMethodValidator for
  // the given name exclusively from the cache. If one is not found in the cache
  // nil is returned.