#vulnerable code 
                                public Response executeWithRetry(Request request) {
        Response response = null;
        RpcException exception = null;
        int currentTryTimes = 0;
        int maxTryTimes = rpcClient.getRpcClientOptions().getMaxTryTimes();
        while (currentTryTimes < maxTryTimes) {
            try {
                // if it is a retry request, add the last selected instance to request,
                // so that load balance strategy can exclude the selected instance.
                // if it is the initial request, not init HashSet, so it is more fast.
                // therefore, it need LoadBalanceStrategy to judge if selectInstances is null.
                if (currentTryTimes > 0) {
                    if (request.getChannel() != null) {
                        if (request.getSelectedInstances() == null) {
                            request.setSelectedInstances(new HashSet<CommunicationClient>(maxTryTimes - 1));
                        }
                        request.getSelectedInstances().add(request.getCommunicationClient());
                    }
                }
                response = rpcClient.execute(request, rpcClient.getCommunicationOptions());
                break;
            } catch (RpcException ex) {
                exception = ex;
                if (exception.getCode() == RpcException.INTERCEPT_EXCEPTION) {
                    break;
                }
            } finally {
                currentTryTimes++;
            }
        }

        if (response.getResult() == null && response.getRpcFuture() == null) {
            if (exception == null) {
                exception = new RpcException(RpcException.UNKNOWN_EXCEPTION, "unknown error");
            }
            throw exception;
        }
        return response;
    } 
                            #location 32 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public Response executeWithRetry(Request request) {
        Response response = null;
        RpcException exception = null;
        int currentTryTimes = 0;
        int maxTryTimes = rpcClient.getRpcClientOptions().getMaxTryTimes();
        while (currentTryTimes < maxTryTimes) {
            try {
                // if it is a retry request, add the last selected instance to request,
                // so that load balance strategy can exclude the selected instance.
                // if it is the initial request, not init HashSet, so it is more fast.
                // therefore, it need LoadBalanceStrategy to judge if selectInstances is null.
                if (currentTryTimes > 0) {
                    if (request.getChannel() != null) {
                        if (request.getSelectedInstances() == null) {
                            request.setSelectedInstances(new HashSet<CommunicationClient>(maxTryTimes - 1));
                        }
                        request.getSelectedInstances().add(request.getCommunicationClient());
                    }
                }
                response = rpcClient.execute(request, rpcClient.getCommunicationOptions());
                break;
            } catch (RpcException ex) {
                exception = ex;
                if (exception.getCode() == RpcException.INTERCEPT_EXCEPTION) {
                    break;
                }
            } finally {
                currentTryTimes++;
            }
        }

        if (response == null || (response.getResult() == null && response.getRpcFuture() == null)) {
            if (exception == null) {
                exception = new RpcException(RpcException.UNKNOWN_EXCEPTION, "unknown error");
            }
            throw exception;
        }
        return response;
    }