BAEL-4956: add source code for describing REST API in swagger

spring-boot-modules/spring-boot-swagger/src/main/java/com/baeldung/apiswagger/Application.java

@@ -0,0 +1,12 @@
+package com.baeldung.apiswagger;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication()
+public class Application {
+
+    public static void main(String[] args) {
+        SpringApplication.run(Application.class, args);
+    }
+}

spring-boot-modules/spring-boot-swagger/src/main/java/com/baeldung/apiswagger/config/SwaggerConfiguration.java

@@ -0,0 +1,26 @@
+package com.baeldung.apiswagger.config;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import springfox.documentation.builders.PathSelectors;
+import springfox.documentation.builders.RequestHandlerSelectors;
+import springfox.documentation.service.Tag;
+import springfox.documentation.spi.DocumentationType;
+import springfox.documentation.spring.web.plugins.Docket;
+
+@Configuration
+public class SwaggerConfiguration {
+
+    public static final String BOOK_TAG = "book service";
+
+    @Bean
+    public Docket api() {
+        return new Docket(DocumentationType.SWAGGER_2)
+          .select()
+          .apis(RequestHandlerSelectors.any())
+          .paths(PathSelectors.any())
+          .build()
+          .tags(new Tag(BOOK_TAG, "the book API with description api tag"));
+    }
+
+}

spring-boot-modules/spring-boot-swagger/src/main/java/com/baeldung/apiswagger/controller/BookController.java

@@ -0,0 +1,21 @@
+package com.baeldung.apiswagger.controller;
+
+import com.baeldung.apiswagger.config.SwaggerConfiguration;
+import io.swagger.annotations.Api;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+import java.util.Arrays;
+import java.util.List;
+
+@RestController
+@RequestMapping("/api/book")
+@Api(tags = {SwaggerConfiguration.BOOK_TAG})
+public class BookController {
+
+    @GetMapping("/")
+    public List<String> getBooks() {
+        return Arrays.asList("book1", "book2");
+    }
+}