Spring Boot 3 & Cloud Native Microservices: 2026 Architecture Guide

# application.properties (Spring Boot 3.2+)
spring.threads.virtual.enabled=true

// Java Configuration for custom TaskExecutors
@Configuration
public class ThreadConfig {
  @Bean
  public AsyncTaskExecutor applicationTaskExecutor() {
    return new TaskExecutorAdapter(Executors.newVirtualThreadPerTaskExecutor());
  }
}

@Service
public class PaymentServiceClient {

  @CircuitBreaker(name = "paymentService", fallbackMethod = "paymentFallback")
  @Retry(name = "paymentService")
  public PaymentResponse processPayment(PaymentRequest request) {
    return restClient.post()
      .uri("/api/v1/charge")
      .body(request)
      .retrieve()
      .body(PaymentResponse.class);
  }

  // Fallback must match original method parameters + Throwable
  public PaymentResponse paymentFallback(PaymentRequest request, Throwable ex) {
    log.warn("Payment service unavailable, queuing for offline reconciliation: {}", ex.getMessage());
    return PaymentResponse.queued(request.getTransactionId());
  }
}