WebConfig fails

gistfile1.java

package cuenation.api;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.mongodb.repository.config.EnableMongoRepositories;
import org.springframework.data.web.config.EnableSpringDataWebSupport;
import org.springframework.web.filter.ShallowEtagHeaderFilter;

import javax.servlet.Filter;

@ComponentScan
@EnableAutoConfiguration
@EnableMongoRepositories
@EnableSpringDataWebSupport
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }

    @Configuration
    public class WebConfig {

        public WebConfig() {
        }

        @Bean
        public Filter shallowEtagHeaderFilter() {
            return new ShallowEtagHeaderFilter();
        }
    }

}