Fix test failures in data-rest-validation and data-rest-composite-id

- data-rest-validation: Add missing spring-boot-restclient dependency and replace
  ValidationError with local DTO (Spring Data REST 5.x made constructor private)
- data-rest-composite-id: Restore @GeneratedValue on Author.Id.id field (erroneously
  removed by OpenRewrite recipe during Spring Boot 4 upgrade)

Agent-Logs-Url: https://github.com/rashidi/spring-boot-tutorials/sessions/b0bdf128-5dc8-4e3a-a405-e09e45e57664

Co-authored-by: rashidi <380073+rashidi@users.noreply.github.com>

Author: Copilot

data-rest-composite-id/src/main/java/zin/rashidi/datarest/compositeid/book/Author.java

@@ -19,6 +19,7 @@ class Author {
     @Embeddable
     static class Id implements Serializable {
 
+        @GeneratedValue
         private Long id;
 
         public Long id() {

data-rest-validation/build.gradle.kts

@@ -22,6 +22,7 @@ dependencies {
     implementation("org.springframework.boot:spring-boot-starter-data-mongodb")
     implementation("org.springframework.boot:spring-boot-starter-data-rest")
     runtimeOnly("com.mysql:mysql-connector-j")
+    testImplementation("org.springframework.boot:spring-boot-restclient")
     testImplementation("org.springframework.boot:spring-boot-resttestclient")
     testImplementation("org.springframework.boot:spring-boot-starter-test")
     testImplementation("org.springframework.boot:spring-boot-testcontainers")

data-rest-validation/src/test/java/zin/rashidi/boot/data/rest/book/CreateBookTests.java

@@ -17,7 +17,6 @@
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.resttestclient.TestRestTemplate;
 import org.springframework.context.annotation.Import;
-import org.springframework.data.rest.webmvc.support.RepositoryConstraintViolationExceptionMessage.ValidationError;
 import org.springframework.http.HttpEntity;
 import org.springframework.http.HttpHeaders;
 
@@ -75,6 +74,35 @@ private HttpHeaders headers() {
         return headers;
     }
 
+    static class ValidationError {
+
+        private String entity;
+        private String property;
+        private Object invalidValue;
+        private String message;
+
+        public String getMessage() {
+            return message;
+        }
+
+        public void setEntity(String entity) {
+            this.entity = entity;
+        }
+
+        public void setProperty(String property) {
+            this.property = property;
+        }
+
+        public void setInvalidValue(Object invalidValue) {
+            this.invalidValue = invalidValue;
+        }
+
+        public void setMessage(String message) {
+            this.message = message;
+        }
+
+    }
+
     static class RepositoryRestErrorResponse {
 
         private List<ValidationError> errors = new ArrayList<>();