在SpringBoot Web响应中返回空字符串而不是null

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class MyController {

    @GetMapping("/example")
    @ResponseBody
    public String example() {
        return "";
    }
}

import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class MyController {

    @GetMapping("/example")
    public ResponseEntity<String> example() {
        return ResponseEntity.ok("");
    }
}