In IntellIJ not long ago I was able to make changes to my html/thymeleaf files and hit 'Build Project' and Spring Boot didn't have to restart the entire app. It would showcase the changes in my web browser (Firefox, Chrome). I have researched and tried a variety of changes and can't seem to find the issue/error to get me back to faster, efficient frontend productivity.
It's only a setting inside of IntelliJ Idea. You can see here what you need to set, and to have in a build.gradle or pom file.