application.properties doesn't work for the official example gs-rest-service-main.zip, how do I do?

Question

As far as I know, "application.properties" are used as configuration in spring projects.

Usually, I download the starter projects from https://start.spring.io/ for which "application.properties" works well.

However, I for the the official example https://github.com/spring-guides/gs-rest-service "application.properties" doesn't work.

I added a file named "application.properties" and add one entry to it.

the terminal window output the info logging anyway, which indicates "application.properties" doesn't work. What am I missing?