fix(项目管理-迭代): #11202 迭代燃尽图兼容返回

microservices-modules/microservices-modules-pms/src/main/java/com/microservices/pms/project/service/impl/PmsProjectSprintServiceImpl.java

@@ -235,6 +235,9 @@ public class PmsProjectSprintServiceImpl implements IPmsProjectSprintService
         if (pmsProjectSprint == null) {
             throw new ServiceException("该迭代不存在(迭代ID[%s])", pmSprintId);
         }
+        if (pmsProjectSprint.getStartTime() == null || pmsProjectSprint.getEndTime() == null) {
+            return null;
+        }
         JSONObject result = gitLinkRequestHelper.doGet(
                 PmsGitLinkRequestUrl.GET_SPRINT_BURN_DOWN_CHART(pmSprintId,
                         pmsProjectSprint.getStartTime(),