public void setAuthenticationStrategy(AuthenticationStrategy authenticationStrategy) {
        this.authenticationStrategy = authenticationStrategy;
    }
Allows overriding the default {@code AuthenticationStrategy} utilized during multi-realm log-in attempts.
This object is only used when two or more Realms are configured.

@param authenticationStrategy the strategy implementation to use during log-in attempts.
@since 0.2
core/src/main/java/org/apache/shiro/authc/pam/ModularRealmAuthenticator.java