Move articles from spring-core-6 module to other spring-boot modules (#13722)

* Move articles from spring-core-6 module to other spring-boot modules

* JAVA-19559 Move articles from spring-core-6 module to other spring-boot-3 modules

* JAVA-19559 Minor spacing change

* JAVA-19559 Revert  Minor spacing change

spring-boot-modules/spring-boot-3/src/main/java/com/baeldung/httpinterface/Book.java

@@ -0,0 +1,3 @@
+package com.baeldung.httpinterface;
+
+public record Book(long id, String title, String author, int year) {}

spring-boot-modules/spring-boot-3/src/main/java/com/baeldung/httpinterface/BooksClient.java

@@ -0,0 +1,23 @@
+package com.baeldung.httpinterface;
+
+import org.springframework.stereotype.Component;
+import org.springframework.web.reactive.function.client.WebClient;
+import org.springframework.web.reactive.function.client.support.WebClientAdapter;
+import org.springframework.web.service.invoker.HttpServiceProxyFactory;
+
+@Component
+public class BooksClient {
+
+    private final BooksService booksService;
+
+    public BooksClient(WebClient webClient) {
+        HttpServiceProxyFactory httpServiceProxyFactory =
+          HttpServiceProxyFactory.builder(WebClientAdapter.forClient(webClient))
+            .build();
+        booksService = httpServiceProxyFactory.createClient(BooksService.class);
+    }
+
+    public BooksService getBooksService() {
+        return booksService;
+    }
+}

spring-boot-modules/spring-boot-3/src/main/java/com/baeldung/httpinterface/BooksService.java

@@ -0,0 +1,26 @@
+package com.baeldung.httpinterface;
+
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.PathVariable;
+import org.springframework.web.bind.annotation.RequestBody;
+import org.springframework.web.service.annotation.DeleteExchange;
+import org.springframework.web.service.annotation.GetExchange;
+import org.springframework.web.service.annotation.PostExchange;
+
+import java.util.List;
+
+interface BooksService {
+
+    @GetExchange("/books")
+    List<Book> getBooks();
+
+    @GetExchange("/books/{id}")
+    Book getBook(@PathVariable("id") long id);
+
+    @PostExchange("/books")
+    Book saveBook(@RequestBody Book book);
+
+    @DeleteExchange("/books/{id}")
+    ResponseEntity<Void> deleteBook(@PathVariable("id") long id);
+
+}