ApiGatewayApplication.java

package com.checkout.paymentgw.gateway;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

/**
 * The single public entry point.
 *
 * <p>Responsibilities (configured in {@code application.yml}):
 * <ul>
 *   <li>Routing: {@code POST /api/payments}  → {@code payment-service}</li>
 *   <li>Routing: {@code GET  /api/payments/{id}} → {@code payment-query-service}</li>
 *   <li>JWT validation (Spring Security resource server)</li>
 *   <li>Redis-backed rate limiting (per merchant + IP)</li>
 *   <li>Correlation-id injection</li>
 *   <li>CORS, request logging</li>
 * </ul>
 *
 * <p><strong>Anti-pattern alert:</strong> the gateway must remain config-heavy and
 * code-light. Business decisions belong inside services.
 */
@SpringBootApplication
public class ApiGatewayApplication {

    public static void main(String[] args) {
        SpringApplication.run(ApiGatewayApplication.class, args);
    }
}