如何返回我的自定义json文件，而不是生成spring boot的默认json文件？

<dependencies>
    <!-- Spring Web -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <!-- Jackson -->
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
    </dependency>
</dependencies>

@RestController
@RequestMapping("/api")
public class MyController {
    // 处理GET请求，返回自定义的JSON文件
    @GetMapping("/custom-json")
    public ResponseEntity<Object> getCustomJson() {
        // 构建自定义的JSON数据
        Map<String, Object> jsonData = new HashMap<>();
        jsonData.put("message", "Hello, World!");
        jsonData.put("timestamp", new Date());

        // 返回自定义的JSON数据
        return ResponseEntity.ok(jsonData);
    }
}