https://stackoverflow.com/questions/21399586/hot-swapping-in-spring-boot
Getting Started | Serving Web Content with Spring MVC
Spring Boot Devtools
A common feature of developing web applications is coding a change, restarting your application, and refreshing the browser to view the change. This entire process can eat up a lot of time. To speed up this refresh cycle, Spring Boot offers with a handy module known as spring-boot-devtools. Spring Boot Devtools:
Enables hot swapping.
Switches template engines to disable caching.
Enables LiveReload to automatically refresh the browser.
Other reasonable defaults based on development instead of production.