combine servlet init in application

Author: barnhill

src/main/java/com/pnuema/java/barcode/barcodeapi/BarcodeApiApplication.java

@@ -4,6 +4,8 @@
 import io.swagger.v3.oas.annotations.servers.Server;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.builder.SpringApplicationBuilder;
+import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
 import org.springframework.cache.annotation.EnableCaching;
 import org.springframework.context.annotation.Bean;
 import org.springframework.web.filter.ShallowEtagHeaderFilter;
@@ -15,11 +17,16 @@
 })
 @SpringBootApplication
 @EnableCaching
-public class BarcodeApiApplication {
+public class BarcodeApiApplication extends SpringBootServletInitializer {
     public static void main(String[] args) {
         SpringApplication.run(BarcodeApiApplication.class, args);
     }
 
+    @Override
+    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
+        return application.sources(BarcodeApiApplication.class);
+    }
+
     @Bean
     public ShallowEtagHeaderFilter shallowEtagHeaderFilter() {
         ShallowEtagHeaderFilter filter = new ShallowEtagHeaderFilter();