Upgrade to Spring Boot 3.5.6 and migrate to Jakarta EE

[devin-ai-integration]

Upgrade to Spring Boot 3.5.6 and migrate to Jakarta EE

Summary

Upgraded all 7 microservices from Spring Boot 2.7.14/2.7.15 to Spring Boot 3.5.6 with complete Jakarta EE namespace migration. This includes updating Spring Cloud from 2021.0.8 to 2025.0.0, Keycloak from 21.0.1 to 22.0.5, and handling all breaking changes from the major version upgrade.

Services upgraded:

• API-Gateway
• Account-Service
• Fund-Transfer
• Sequence-Generator
• Service-Registry
• Transaction-Service
• User-Service

Key changes:

• ✅ Updated all pom.xml files with Spring Boot 3.5.6 and Spring Cloud 2025.0.0
• ✅ Migrated javax.persistence.* → jakarta.persistence.* in all entity classes
• ✅ Migrated javax.transaction.Transactional → jakarta.transaction.Transactional
• ✅ Updated GlobalExceptionHandler method signatures for Spring Framework 6.x compatibility (HttpStatus → HttpStatusCode)
• ✅ Replaced Apache Commons IOUtils with standard Java BufferedReader (no longer a transitive dependency)
• ✅ Updated API Gateway SecurityConfig to use lambda-based configuration for Spring Security 6.x
• ✅ Removed deprecated @EnableEurekaClient annotation (auto-registration now default)
• ✅ All services compile successfully
• ✅ Unit tests pass for Service-Registry, Sequence-Generator, and API-Gateway

Review & Testing Checklist for Human

⚠️ IMPORTANT: While all services compile and unit tests pass, this is a major version upgrade with significant runtime behavior changes that cannot be fully validated without integration testing. Please thoroughly test the following:

• End-to-end authentication flow - Test OAuth2/JWT authentication through the API Gateway. The SecurityConfig was updated to use lambda-based configuration for Spring Security 6.x. Verify login, token validation, and protected endpoints still work correctly.

• Keycloak integration - Test user registration and management in User-Service. The Keycloak admin client was upgraded from 21.0.1 to 22.0.5. Verify user creation, updates, and authentication against Keycloak work as expected.

• Service discovery - Verify all services register with Eureka correctly. The @EnableEurekaClient annotation was removed (deprecated in Spring Cloud 2022.x+) and registration should happen automatically. Check the Eureka dashboard to confirm all 7 services appear.

• Feign client error handling - Test API error responses across services. The FeignClientErrorDecoder in Account-Service, Fund-Transfer, and Transaction-Service was updated to use BufferedReader instead of Apache Commons IOUtils. Verify error responses are still parsed and propagated correctly.

• Database operations - Test CRUD operations in all services that use JPA (Account-Service, Fund-Transfer, Sequence-Generator, Transaction-Service, User-Service). The Jakarta persistence namespace migration should be transparent, but verify entity mappings and database operations work correctly.

Test Plan

1. Start all services in this order: Service-Registry → Sequence-Generator → API-Gateway → User-Service → Account-Service → Fund-Transfer → Transaction-Service
2. Verify all services register with Eureka
3. Test user registration through the API Gateway
4. Test account creation, fund transfers, and transaction queries
5. Verify error responses are properly formatted when validation fails or exceptions occur

Notes

• ⚠️ Configuration warning: The tests show deprecation warnings for Spring Cloud Gateway route configuration. The spring.cloud.gateway.routes[*] keys should be migrated to spring.cloud.gateway.server.webflux.routes[*] in a follow-up PR to avoid future compatibility issues.
• Unit tests for User-Service, Account-Service, Fund-Transfer, and Transaction-Service were not run as they require external dependencies (MySQL, Keycloak) which were not available in the test environment.
• All Lombok @EqualsAndHashCode warnings about missing callSuper are pre-existing and not introduced by this PR.

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Link to Devin run: https://app.devin.ai/sessions/d5242c4b58d449648bee8814f0d60d94
Requested by: Sam Fertig (@samfert-codeium)

[devin-ai-integration]

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