feat: Enhance Concept Service with validation and auditing configuration

- Added Spring Boot validation dependency to support input validation for CRUD operations.
- Updated implementation plan to reflect completion of phases 1-9, confirming the service is fully implemented and production-ready.
- Introduced `JpaConfig` class to enable JPA auditing with a custom date-time provider, ensuring accurate timestamping for entity changes.
- Removed unnecessary `@EnableJpaAuditing` annotation from `ConceptSvc` class.

Author: lennyStreavent

concept-svc/IMPLEMENTATION_PLAN.md

@@ -3,7 +3,7 @@
 ## Overview
 Implementation of the Concept Service following patterns established by the User Service. The service will handle event concept CRUD operations, PDF generation, and integrate with AI suggestions through the standard update endpoint.
 
-**Status: Phases 1-8 Complete** - The core concept service is fully implemented and ready for testing.
+**Status: Phases 1-9 Complete** - The concept service is fully implemented, tested, and production-ready.
 
 ## Phase 1: Database & Infrastructure Setup
 
@@ -135,17 +135,44 @@ Implementation of the Concept Service following patterns established by the User
 ## Phase 9: Testing & Validation
 
 ### 9.1 Basic Testing
-- [ ] Test all CRUD endpoints with Postman/curl
-- [ ] Test JWT authentication integration
-- [ ] Test user isolation (users can only see their concepts)
-- [ ] Test PDF generation functionality
-- [ ] Test error scenarios (invalid IDs, unauthorized access)
+- [x] Test all CRUD endpoints with Postman/curl
+  - [x] GET /health - Service health check ✅
+  - [x] GET /api/concepts - List concepts with pagination ✅
+  - [x] POST /api/concepts - Create concept with initial requirements ✅
+  - [x] GET /api/concepts/{id} - Get concept by ID ✅
+  - [x] PUT /api/concepts/{id} - Update concept ✅
+  - [x] DELETE /api/concepts/{id} - Soft delete (ARCHIVED) ✅
+  - [x] GET /api/concepts/{id}/pdf - Download PDF ✅
+  - [x] POST /api/concepts/{id}/apply-suggestion - Mock AI suggestions ✅
+- [x] Test JWT authentication integration
+  - [x] 401 for missing token ✅
+  - [x] 401 for invalid token ✅
+  - [x] Valid token authentication ✅
+- [x] Test user isolation (users can only see their concepts)
+  - [x] Ownership verification with findByIdAndUserId() ✅
+  - [x] 404 for non-existent/not-owned concepts ✅
+- [x] Test PDF generation functionality
+  - [x] Correct headers and content-disposition ✅
+  - [x] PDF content with concept details ✅
+- [x] Test error scenarios (invalid IDs, unauthorized access)
+  - [x] Security best practices - no information leakage ✅
+  - [x] Proper ErrorResponse objects ✅
 
 ### 9.2 Integration Testing
-- [ ] Test with Docker Compose setup
-- [ ] Verify database connectivity and data persistence
-- [ ] Test frontend integration with concept service
-- [ ] Verify suggestion workflow through update endpoint
+- [x] Test with Docker Compose setup
+  - [x] Fixed validation dependency and JPA audit configuration ✅
+  - [x] PostgreSQL database connectivity ✅
+  - [x] Service builds and starts successfully ✅
+- [x] Verify database connectivity and data persistence
+  - [x] Concept creation persists correctly ✅
+  - [x] Updates increment version and timestamp ✅
+  - [x] Soft delete changes status to ARCHIVED ✅
+- [x] Test frontend integration with concept service
+  - [x] CORS and security headers working ✅
+  - [x] OpenAPI-compliant JSON responses ✅
+- [x] Verify suggestion workflow through update endpoint
+  - [x] Mock AI suggestion endpoint working ✅
+  - [x] Notes field updated correctly ✅
 
 ## Phase 10: Deployment & Documentation
 

concept-svc/build.gradle

@@ -34,6 +34,9 @@ dependencies {
 	// PDF generation
 	implementation 'com.itextpdf:itext7-core:7.2.5'
 
+	// Validation
+	implementation 'org.springframework.boot:spring-boot-starter-validation'
+	
 	// OpenAPI generated code dependencies
 	implementation 'org.openapitools:jackson-databind-nullable:0.2.6'
 	implementation 'io.swagger.core.v3:swagger-annotations:2.2.20'

concept-svc/src/main/java/de/tum/aet/devops25/conceptsvc/ConceptSvc.java

@@ -2,10 +2,8 @@
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
-import org.springframework.data.jpa.repository.config.EnableJpaAuditing;
 
 @SpringBootApplication
-@EnableJpaAuditing
 public class ConceptSvc {
 
 	public static void main(String[] args) {

concept-svc/src/main/java/de/tum/aet/devops25/conceptsvc/JpaConfig.java

@@ -0,0 +1,19 @@
+package de.tum.aet.devops25.conceptsvc;
+
+import java.time.OffsetDateTime;
+import java.util.Optional;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.auditing.DateTimeProvider;
+import org.springframework.data.jpa.repository.config.EnableJpaAuditing;
+
+@Configuration
+@EnableJpaAuditing(dateTimeProviderRef = "auditingDateTimeProvider")
+public class JpaConfig {
+
+    @Bean
+    public DateTimeProvider auditingDateTimeProvider() {
+        return () -> Optional.of(OffsetDateTime.now());
+    }
+}