如何在ResponseEntity中不返回空值？

@GetMapping("/data")
public ResponseEntity<String> getData() {
    Optional<String> data = Optional.ofNullable(someService.getData());
    return ResponseEntity.ok(data.orElse("No data available"));
}

public class ResponseWrapper<T> {
    private boolean hasData;
    private T data;

    // getters and setters
}

@GetMapping("/data")
public ResponseEntity<ResponseWrapper<String>> getData() {
    ResponseWrapper<String> response = new ResponseWrapper<>();
    String data = someService.getData();
    if (data != null) {
        response.setHasData(true);
        response.setData(data);
    } else {
        response.setHasData(false);
    }
    return ResponseEntity.ok(response);
}

public class EmptyValueException extends RuntimeException {
    // constructors
}

@ControllerAdvice
public class GlobalExceptionHandler {
    @ExceptionHandler(EmptyValueException.class)
    public ResponseEntity<String> handleEmptyValueException(EmptyValueException ex) {
        return ResponseEntity.status(HttpStatus.NOT_FOUND).body("No data available");
    }
}

@GetMapping("/data")
public ResponseEntity<String> getData() {
    String data = someService.getData();
    if (data == null) {
        throw new EmptyValueException();
    }
    return ResponseEntity.ok(data);
}