#vulnerable code 
                              private void doDeploy() {
    // TODO: The number of ackers is configurable, but the auditor
    // verticle needs to be refactored to better support this.
    // So, for now we just deploy a single auditor verticle.
    JsonObject ackConfig = new JsonObject().putString("address", context.auditAddress())
      .putString("broadcast", context.broadcastAddress())
      .putBoolean("enabled", context.getDefinition().ackingEnabled())
      .putNumber("expire", context.getDefinition().ackExpire());

    deployVerticle(Auditor.class.getName(), ackConfig, new Handler<AsyncResult<String>>() {
        @Override
        public void handle(AsyncResult<String> result) {
          if (result.failed()) {
            logger.error("Failed to deploy authenticator verticle.", result.cause());
            container.exit();
          }
          else {
            authDeploymentId = result.result();
            new RecursiveDeployer(context).deploy(new Handler<AsyncResult<Void>>() {
              @Override
              public void handle(AsyncResult<Void> result) {
                if (result.failed()) {
                  container.logger().error("Failed to deploy network.", result.cause());
                  container.exit();
                }
              }
            });
          }
        }
    });
  } 
                            #location 8 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                              private void doDeploy() {
    recursiveDeployAuditors(context.getAuditors(), new DefaultFutureResult<Void>().setHandler(new Handler<AsyncResult<Void>>() {
      @Override
      public void handle(AsyncResult<Void> result) {
        if (result.failed()) {
          logger.error("Failed to deploy auditor verticle.", result.cause());
          container.exit();
        }
        else {
          new RecursiveDeployer(context).deploy(new Handler<AsyncResult<Void>>() {
            @Override
            public void handle(AsyncResult<Void> result) {
              if (result.failed()) {
                container.logger().error("Failed to deploy network.", result.cause());
                container.exit();
              }
            }
          });
        }
      }
    }));
  }