public AuthenticationInfo afterAttempt(Realm realm, AuthenticationToken token,
                                           AuthenticationInfo singleRealmInfo, AuthenticationInfo aggregateInfo,
                                           Throwable t) throws AuthenticationException {
        AuthenticationInfo info;
        if (singleRealmInfo == null) {
            info = aggregateInfo;
        } else {
            if (aggregateInfo == null) {
                info = singleRealmInfo;
            } else {
                info = merge(singleRealmInfo, aggregateInfo);
            }
        }

        return info;
    }
Base implementation that will aggregate the specified <code>singleRealmInfo</code> into the
<code>aggregateInfo</code> and then returns the aggregate.  Can be overridden by subclasses for custom behavior.
core/src/main/java/org/apache/shiro/authc/pam/AbstractAuthenticationStrategy.java