文件作答bug fix

examcloud-core-oe-student-api-provider/src/main/java/cn/com/qmth/examcloud/core/oe/student/api/controller/ExamControlController.java

@@ -222,7 +222,7 @@ public class ExamControlController extends ControllerSupport {
     public void saveUploadedFileAcknowledgeStatus(@RequestBody @Valid SaveUploadedFileAcknowledgeStatusReq req) {
         String acknowledgeId = RedisKeyHelper.getBuilder().studentFileAnswerKey(req.getExamRecordDataId(), req.getOrder());
         ExamFileAnswer fileAnswer = examFileAnswerService.getFileAnswer(acknowledgeId);
-        if (null != fileAnswer) {
+        if (null == fileAnswer) {
             throw new StatusException("100010", "无效的数据");
         }