这是我的Spring Boot 控制器的样子

@RestController
public class WhatsappController {
    private final String VERIFICATION_TOKEN = "12345";

    @GetMapping("/webhook")
    public ResponseEntity<String> verifyWebhook(@RequestParam("hub.mode") String mode,
                                                @RequestParam("hub.challenge") String challenge,
                                                @RequestParam("hub.verify_token") String token) {
        if (mode.equals("subscribe") && token.equals(VERIFICATION_TOKEN)) {
            return new ResponseEntity<>(challenge, HttpStatus.OK);
        } else {
            return new ResponseEntity<>("Verification token or mode mismatch", HttpStatus.FORBIDDEN);
        }
    }
}

但是当我用whatsapp配置ngrok url时，它说“回调URL或验证令牌无法验证。请验证提供的信息或稍后重试。”
请告诉我我做错了什么！