fix：【bpm】只能退回到已经处理过的节点（排除审批未经过的节点）。相关 issue：https://github.com/YunaiV/ruoyi-vue-pro/issues/982

yudao-module-bpm/src/main/java/cn/iocoder/yudao/module/bpm/service/task/BpmTaskServiceImpl.java

@@ -376,6 +376,11 @@ public class BpmTaskServiceImpl implements BpmTaskService {
         }
         // 2.2 过滤：只有串行可到达的节点，才可以退回。类似非串行、子流程无法退回
         previousUserList.removeIf(userTask -> !BpmnModelUtils.isSequentialReachable(source, userTask, null));
+
+        // 2.3 过滤：只能退回到已经处理过的节点（排除审批未经过的节点）。相关 issue：https://github.com/YunaiV/ruoyi-vue-pro/issues/982
+        List<HistoricTaskInstance> finishedTasks = getFinishedTaskListByProcessInstanceIdWithoutCancel(task.getProcessInstanceId());
+        Set<String> finishedTaskDefinitionKeys = convertSet(finishedTasks, HistoricTaskInstance::getTaskDefinitionKey);
+        previousUserList.removeIf(userTask -> !finishedTaskDefinitionKeys.contains(userTask.getId()));
         return previousUserList;
     }