output: #fixed code
                                  @Override
      public void startAppiumServer(String host) throws Exception {
          System.out.println(
                  "**************************************************************************\n");
          System.out.println("Starting Appium Server on host " + host);
          System.out.println(
                  "**************************************************************************\n");
          String serverPath = CapabilityManager.getInstance().getAppiumServerPath(host);
          String serverPort = CapabilityManager.getInstance().getAppiumServerPort(host);
          if (serverPath == null
                  && serverPort == null) {
              System.out.println("Picking Default Path for AppiumServiceBuilder");
              new Api().getResponse("http://" + host + ":4567"
                      + "/appium/start").body().string();
          } else if (serverPath != null && serverPort != null ) {
              System.out.println("Picking UserSpecified Path & Port for AppiumServiceBuilder");
              new Api().getResponse("http://" + host + ":4567"
                      + "/appium/start?URL=" + serverPath
                      + "&PORT=" + serverPort).body().string();
          } else if (serverPath != null) {
              System.out.println("Picking UserSpecified Path & Using default Port for AppiumServiceBuilder");
              new Api().getResponse("http://" + host + ":4567"
                      + "/appium/start?URL=" + serverPath).body().string();
          } else if (serverPort != null) {
              System.out.println("Picking Default Path & User Port for AppiumServiceBuilder");
              new Api().getResponse("http://" + host + ":4567"
                      + "/appium/start?PORT=" + serverPort).body().string();
          }
  
          boolean status = Boolean.getBoolean(new JSONObject(new Api().getResponse("http://" + host + ":4567"
                  + "/appium/isRunning").body().string()).get("status").toString());
          if (status) {
              System.out.println(
                      "***************************************************************\n");
              System.out.println("Appium Server started successfully on  " + host);
              System.out.println(
                      "****************************************************************\n");
          }
      }
input: #vulnerable code 
                                  @Override
      public void startAppiumServer(String host) throws Exception {
          System.out.println(
                  "**************************************************************************\n");
          System.out.println("Starting Appium Server on host " + host);
          System.out.println(
                  "**************************************************************************\n");
          if (CapabilityManager.getInstance().getAppiumServerPath(host) == null) {
              System.out.println("Picking Default Path for AppiumServiceBuilder");
              new Api().getResponse("http://" + host + ":4567"
                      + "/appium/start").body().string();
          } else {
              System.out.println("Picking UserSpecified Path for AppiumServiceBuilder");
              String appiumServerPath = CapabilityManager.getInstance().getAppiumServerPath(host);
              new Api().getResponse("http://" + host + ":4567"
                      + "/appium/start?URL=" + appiumServerPath).body().string();
          }
  
          boolean status = Boolean.getBoolean(new JSONObject(new Api().getResponse("http://" + host + ":4567"
                  + "/appium/isRunning").body().string()).get("status").toString());
          if (status) {
              System.out.println(
                      "***************************************************************\n");
              System.out.println("Appium Server started successfully on  " + host);
              System.out.println(
                      "****************************************************************\n");
          }
      } 
                              #location 11 
                              #vulnerability type NULL_DEREFERENCE