#fixed code
                                private static void add(Set<String> doNotRemovePaths, DashBoard dash, EnhancedHistoryGraph graph) {
        for (GraphDataStream graphDataStream : graph.dataStreams) {
            if (graphDataStream != null && graphDataStream.dataStream != null && graphDataStream.dataStream.isValid()) {
                DataStream dataStream = graphDataStream.dataStream;
                Target target = dash.getTarget(graphDataStream.targetId);
                if (target != null) {
                    for (int deviceId : target.getAssignedDeviceIds()) {
                        for (GraphGranularityType type : GraphGranularityType.values()) {
                            String filename = ReportingDao.generateFilename(dash.id,
                                    deviceId,
                                    dataStream.pinType.pintTypeChar, dataStream.pin, type.label);
                            doNotRemovePaths.add(filename);
                        }
                    }
                }
            }
        }
    }
#vulnerable code 
                                private static void add(Set<String> doNotRemovePaths, DashBoard dash, EnhancedHistoryGraph graph) {
        for (GraphDataStream graphDataStream : graph.dataStreams) {
            if (graphDataStream != null && graphDataStream.dataStream != null && graphDataStream.dataStream.isValid()) {
                DataStream dataStream = graphDataStream.dataStream;
                Target target = dash.getTarget(graphDataStream.targetId);
                for (int deviceId : target.getAssignedDeviceIds()) {
                    for (GraphGranularityType type : GraphGranularityType.values()) {
                        String filename = ReportingDao.generateFilename(dash.id,
                                deviceId,
                                dataStream.pinType.pintTypeChar, dataStream.pin, type.label);
                        doNotRemovePaths.add(filename);
                    }
                }
            }
        }
    } 
                            #location 6 
                            #vulnerability type NULL_DEREFERENCE