#vulnerable code 
                              @SuppressWarnings({"unchecked", "rawtypes"})
  public void onReceive(ServiceContext serviceContext) throws Throwable {
    FlowMessage fm = serviceContext.getFlowMessage();
    if (serviceContext.isSync() && !syncActors.containsKey(serviceContext.getId())) {
      syncActors.putIfAbsent(serviceContext.getId(), getSender());
    }

    // TODO 没有必要设置默认值,下面执行异常就会抛出异常
    Object result = null;// DefaultMessage.getMessage();// set default
    try {
      this.service = ServiceFactory.getService(serviceName);
      result = ((Service) service).process(fm.getMessage(), serviceContext);
    } catch (Throwable e) {
      Web web = serviceContext.getWeb();
      if (web != null) {
        web.complete();
      }
      throw new FlowerException("fail to invoke service " + serviceName + " : " + service + ", param : " + fm.getMessage(), e);
    }

    if (serviceContext.isSync() && !hasChildActor()) {
      syncActors.get(serviceContext.getId()).tell(result, getSelf());
      syncActors.remove(serviceContext.getId());
      return;
    }

    Web web = serviceContext.getWeb();
    if (service instanceof Complete) {
      // FlowContext.removeServiceContext(fm.getTransactionId());
    }
    if (web != null) {
      if (service instanceof Flush) {
        web.flush();
      }
      if (service instanceof HttpComplete || service instanceof Complete) {
        web.complete();
      }
    }

    if (result == null)// for joint service
      return;
    if (hasChildActor()) {
      for (RefType refType : nextServiceActors) {
        ServiceContext context = serviceContext.newInstance();
        context.getFlowMessage().setMessage(result);
        // if (refType.isJoint()) {
        // FlowMessage flowMessage1 = CloneUtil.clone(fm);
        // flowMessage1.setMessage(result);
        // context.setFlowMessage(flowMessage1);
        // }
        // condition fork for one-service to multi-service
        if (refType.getMessageType().isInstance(result)) {
          if (!(result instanceof Condition) || !(((Condition) result).getCondition() instanceof String)
              || stringInStrings(refType.getServiceName(), ((Condition) result).getCondition().toString())) {
            refType.getActorRef().tell(context, getSelf());
          }
        }
      }
    } else {

    }
  } 
                            #location 45 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                              @SuppressWarnings({"unchecked", "rawtypes"})
  public void onReceive(ServiceContext serviceContext) throws Throwable {
    FlowMessage fm = serviceContext.getFlowMessage();
    if (serviceContext.isSync() && !syncActors.containsKey(serviceContext.getId())) {
      syncActors.putIfAbsent(serviceContext.getId(), getSender());
    }

    // TODO 没有必要设置默认值,下面执行异常就会抛出异常
    Object result = null;// DefaultMessage.getMessage();// set default
    try {
      this.service = ServiceFactory.getService(serviceName);
      result = ((Service) service).process(fm.getMessage(), serviceContext);
    } catch (Throwable e) {
      Web web = serviceContext.getWeb();
      if (web != null) {
        web.complete();
      }
      throw new FlowerException("fail to invoke service " + serviceName + " : " + service + ", param : " + fm.getMessage(), e);
    }

    logger.info("同步处理 ： {}, hasChild : {}", serviceContext.isSync(), hasChildActor());
    if (serviceContext.isSync() && !hasChildActor()) {
      logger.info("返回响应 {}", result);
      ActorRef actor = syncActors.get(serviceContext.getId());
      if(actor !=null) {
        actor.tell(result, getSelf());
        syncActors.remove(serviceContext.getId());
      }
      return;
    }

    Web web = serviceContext.getWeb();
    if (service instanceof Complete) {
      // FlowContext.removeServiceContext(fm.getTransactionId());
    }
    if (web != null) {
      if (service instanceof Flush) {
        web.flush();
      }
      if (service instanceof HttpComplete || service instanceof Complete) {
        web.complete();
      }
    }

    if (result == null)// for joint service
      return;
    if (hasChildActor()) {
      for (RefType refType : nextServiceActors) {
        ServiceContext context = serviceContext.newInstance();
        context.getFlowMessage().setMessage(result);
        // if (refType.isJoint()) {
        // FlowMessage flowMessage1 = CloneUtil.clone(fm);
        // flowMessage1.setMessage(result);
        // context.setFlowMessage(flowMessage1);
        // }
        // condition fork for one-service to multi-service
        if (refType.getMessageType().isInstance(result)) {
          if (!(result instanceof Condition) || !(((Condition) result).getCondition() instanceof String)
              || stringInStrings(refType.getServiceName(), ((Condition) result).getCondition().toString())) {
            refType.getActorRef().tell(context, getSelf());
          }
        }
      }
    } else {

    }
  }