Thymeleaf加入Spring Security標籤的支援

        <dependency>
            <groupId>org.thymeleaf.extras</groupId>
            <artifactId>thymeleaf-extras-springsecurity5</artifactId>
        </dependency>

ref:
https://www.baeldung.com/spring-security-thymeleaf
https://www.thymeleaf.org/doc/articles/springsecurity.html
https://www.marcobehler.com/guides/spring-security

demo code:
https://github.com/imrexhuang/Spring-Boot-Security-Thymeleaf-Demo