#fixed code
                                public void requestTxGroup(NulsDigestData blockHash, String nodeId) {
        GetTxGroupRequest request = new GetTxGroupRequest();
        GetTxGroupParam data = new GetTxGroupParam();
        data.setBlockHash(blockHash);
        List<NulsDigestData> txHashList = new ArrayList<>();

        SmallBlock smb = temporaryCacheManager.getSmallBlock(blockHash.getDigestHex());
        for (NulsDigestData txHash : smb.getTxHashList()) {
            boolean exist = txCacheManager.txExist(txHash);
            if (!exist) {
                txHashList.add(txHash);
            }
        }
        if (txHashList.isEmpty()) {
            BlockHeader header = temporaryCacheManager.getBlockHeader(smb.getBlockHash().getDigestHex());
            if (null == header) {
                return;
            }
            Block block = new Block();
            block.setHeader(header);
            List<Transaction> txs = new ArrayList<>();
            for (NulsDigestData txHash : smb.getTxHashList()) {
                Transaction tx = txCacheManager.getTx(txHash);
                if (null == tx) {
                    throw new NulsRuntimeException(ErrorCode.DATA_ERROR);
                }
                txs.add(tx);
            }
            block.setTxs(txs);
            ValidateResult vResult = block.verify();
            if (vResult.isFailed()&&vResult.getErrorCode()!=ErrorCode.ORPHAN_BLOCK&&vResult.getErrorCode()!=ErrorCode.ORPHAN_TX) {
                return;
            }
            blockManager.addBlock(block, false,nodeId);
            AssembledBlockNotice notice = new AssembledBlockNotice();
            notice.setEventBody(header);
            eventBroadcaster.publishToLocal(notice);
            return;
        }
        data.setTxHashList(txHashList);
        request.setEventBody(data);
        tgRequest.put(blockHash.getDigestHex(), System.currentTimeMillis());
        Integer value = tgRequestCount.get(blockHash.getDigestHex());
        if (null == value) {
            value = 0;
        }
        tgRequestCount.put(blockHash.getDigestHex(), 1 + value);
        if (StringUtils.isBlank(nodeId)) {
            eventBroadcaster.broadcastAndCache(request, false);
        } else {
            eventBroadcaster.sendToNode(request, nodeId);
        }
    }
#vulnerable code 
                                public void requestTxGroup(NulsDigestData blockHash, String nodeId) {
        GetTxGroupRequest request = new GetTxGroupRequest();
        GetTxGroupParam data = new GetTxGroupParam();
        data.setBlockHash(blockHash);
        List<NulsDigestData> txHashList = new ArrayList<>();

        SmallBlock smb = temporaryCacheManager.getSmallBlock(blockHash.getDigestHex());
        for (NulsDigestData txHash : smb.getTxHashList()) {
            boolean exist = txCacheManager.txExist(txHash);
            if (!exist) {
                txHashList.add(txHash);
            }
        }
        if (txHashList.isEmpty()) {
            BlockHeader header = temporaryCacheManager.getBlockHeader(smb.getBlockHash().getDigestHex());
            if (null == header) {
                return;
            }
            Block block = new Block();
            block.setHeader(header);
            List<Transaction> txs = new ArrayList<>();
            for (NulsDigestData txHash : smb.getTxHashList()) {
                Transaction tx = txCacheManager.getTx(txHash);
                if (null == tx) {
                    throw new NulsRuntimeException(ErrorCode.DATA_ERROR);
                }
                txs.add(tx);
            }
            block.setTxs(txs);
            ValidateResult<RedPunishData> vResult = block.verify();
            if (null == vResult || vResult.isFailed()) {
                if (vResult.getLevel() == SeverityLevelEnum.FLAGRANT_FOUL) {
                    RedPunishData redPunishData = vResult.getObject();
                    ConsensusMeetingRunner.putPunishData(redPunishData);
                }
                return;
            }
            blockManager.addBlock(block, false,nodeId);
            AssembledBlockNotice notice = new AssembledBlockNotice();
            notice.setEventBody(header);
            eventBroadcaster.publishToLocal(notice);
            return;
        }
        data.setTxHashList(txHashList);
        request.setEventBody(data);
        tgRequest.put(blockHash.getDigestHex(), System.currentTimeMillis());
        Integer value = tgRequestCount.get(blockHash.getDigestHex());
        if (null == value) {
            value = 0;
        }
        tgRequestCount.put(blockHash.getDigestHex(), 1 + value);
        if (StringUtils.isBlank(nodeId)) {
            eventBroadcaster.broadcastAndCache(request, false);
        } else {
            eventBroadcaster.sendToNode(request, nodeId);
        }
    } 
                            #location 34 
                            #vulnerability type NULL_DEREFERENCE