import org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory;
import org.springframework.boot.web.server.MimeMappings;
import org.springframework.boot.web.servlet.server.ConfigurableServletWebServerFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class TomcatConfig {
	@Bean
	public ConfigurableServletWebServerFactory configurableServletWebServerFactory() {
		TomcatServletWebServerFactory tomcat = new TomcatServletWebServerFactory();

		MimeMappings mappings = new MimeMappings(MimeMappings.DEFAULT);
                mappings.add("wasm", "application/wasm");
                tomcat.setMimeMappings(mappings);

		return tomcat;
	}
}

import org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory;
import org.springframework.boot.web.server.MimeMappings;
import org.springframework.boot.web.server.WebServerFactoryCustomizer;
import org.springframework.stereotype.Component;

@Component
public class ServletCustomizer implements WebServerFactoryCustomizer<TomcatServletWebServerFactory> {
    @Override
    public void customize(TomcatServletWebServerFactory factory) {
        MimeMappings mappings = new MimeMappings(MimeMappings.DEFAULT);
        mappings.add("wasm", "application/wasm");
        factory.setMimeMappings(mappings);
    }
}