如何对'?‘进行编码在url中springboot RestTemplate交换方法？

import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.ResponseEntity;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
import org.springframework.web.client.RestTemplate;
import org.springframework.web.util.UriComponentsBuilder;

public class Main {
    public static void main(String[] args) {
        RestTemplate restTemplate = new RestTemplate();

        // 构建URL
        String url = "http://example.com/api";
        UriComponentsBuilder builder = UriComponentsBuilder.fromHttpUrl(url)
                .queryParam("param", "?");

        // 编码URL
        String encodedUrl = builder.build().encode().toUriString();

        // 构建请求头
        HttpHeaders headers = new HttpHeaders();
        headers.add("Content-Type", "application/json");

        // 发送请求
        HttpEntity<String> entity = new HttpEntity<>(headers);
        ResponseEntity<String> response = restTemplate.exchange(encodedUrl, HttpMethod.GET, entity, String.class);

        // 处理响应
        if (response.getStatusCode().is2xxSuccessful()) {
            String responseBody = response.getBody();
            System.out.println(responseBody);
        }
    }
}