We have developed a static analysis tool NPEDetector to find some potential NPE. Our analysis shows that some callees may return null in corner case(e.g. node crash , IO exception), some of their callers have !=null check but some do not have.
Callee FairScheduler#getAppsInQueue can return null
it has 4 callers, three of them have null checker, one does not have. In this issue we post a patch which can add !=null based on existed !=null check.