Since Spring 5 you just need to implement the interface WebMvcConfigurer:
public class MvcConfig implements WebMvcConfigurer {
This is because Java 8 introduced default methods on interfaces which cover the functionality of the WebMvcConfigurerAdapter class
See here:
https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/web/servlet/config/annotation/WebMvcConfigurerAdapter.html