HTTP/2
Servlet 4 containers are required to support HTTP/2, and Spring Framework 5 is compatible with Servlet API 4. From a programming model perspective, there is nothing specific that applications need to do. However, there are considerations related to server configuration. For more details, see the HTTP/2 wiki page.
Currently, Spring WebFlux does not support HTTP/2 with Netty. There is also no support for pushing resources programmatically to the client.