To enable HTTP/2 support in a Spring Boot app, take these steps:
Add any dependencies necessary for HTTP/2 support, such as spring-boot-starter-tomcat or spring-boot-starter-jetty, which should provide support.
Configure your embedded servlet container so it uses an HTTP/2-capable version of Tomcat or Jetty.
Make sure that your app is only served over HTTPS; HTTP/2 only supports secured connections.
Start the Spring Boot application, which will become accessible using the HTTP/2 protocol.