output: #fixed code
                                  public void loadPackage(String namespace, String ext)
              throws Exception {
          if(fileNames == null){
              fileNames = messageScanner.scannerPackage(namespace, ext);
          }
          // 加载class,获取协议命令
          DefaultClassLoader defaultClassLoader = LocalMananger.getInstance().getLocalSpringServiceManager().getDefaultClassLoader();
          defaultClassLoader.resetDynamicGameClassLoader();
          DynamicGameClassLoader dynamicGameClassLoader = defaultClassLoader.getDynamicGameClassLoader();
  
          if(fileNames != null) {
              for (String fileName : fileNames) {
                  String realClass = namespace
                          + "."
                          + fileName.subSequence(0, fileName.length()
                          - (ext.length()));
  //                Class<?> messageClass = null;
  //                FileClassLoader fileClassLoader = defaultClassLoader.getDefaultClassLoader();
  //                if (!defaultClassLoader.isJarLoad()) {
  //                    defaultClassLoader.initClassLoaderPath(realClass, ext);
  //                    byte[] bytes = fileClassLoader.getClassData(realClass);
  //                    messageClass = dynamicGameClassLoader.findClass(realClass, bytes);
  //                } else {
  //                    //读取 game_server_handler.jar包所在位置
  //                    URL url = ClassLoader.getSystemClassLoader().getResource("./");
  //                    File file = new File(url.getPath());
  //                    File parentFile = new File(file.getParent());
  //                    String jarPath = parentFile.getPath() + File.separator + "lib/game_server_handler.jar";
  //                    logger.info("message load jar path:" + jarPath);
  //                    JarFile jarFile = new JarFile(new File(jarPath));
  //                    fileClassLoader.initJarPath(jarFile);
  //                    byte[] bytes = fileClassLoader.getClassData(realClass);
  //                    messageClass = dynamicGameClassLoader.findClass(realClass, bytes);
  //                }
                  Class<?> messageClass = Class.forName(realClass);
                  logger.info("handler load: " + messageClass);
  
                  IMessageHandler iMessageHandler = getMessageHandler(messageClass);
                  AbstractMessageHandler handler = (AbstractMessageHandler) iMessageHandler;
                  handler.init();
                  Method[] methods = messageClass.getMethods();
                  for (Method method : methods) {
                      if (method.isAnnotationPresent(MessageCommandAnnotation.class)) {
                          MessageCommandAnnotation messageCommandAnnotation = (MessageCommandAnnotation) method
                                  .getAnnotation(MessageCommandAnnotation.class);
                          if (messageCommandAnnotation != null) {
                              addHandler(messageCommandAnnotation.command(), iMessageHandler);
                          }
                      }
                  }
  
              }
          }
      }
input: #vulnerable code 
                                  public void loadPackage(String namespace, String ext)
              throws Exception {
          if(fileNames == null){
              fileNames = messageScanner.scannerPackage(namespace, ext);
          }
          // 加载class,获取协议命令
          DefaultClassLoader defaultClassLoader = LocalMananger.getInstance().getLocalSpringServiceManager().getDefaultClassLoader();
          defaultClassLoader.resetDynamicGameClassLoader();
          DynamicGameClassLoader dynamicGameClassLoader = defaultClassLoader.getDynamicGameClassLoader();
  
          if(fileNames != null) {
              for (String fileName : fileNames) {
                  String realClass = namespace
                          + "."
                          + fileName.subSequence(0, fileName.length()
                          - (ext.length()));
                  Class<?> messageClass = null;
                  FileClassLoader fileClassLoader = defaultClassLoader.getDefaultClassLoader();
                  if (!defaultClassLoader.isJarLoad()) {
                      defaultClassLoader.initClassLoaderPath(realClass, ext);
                      byte[] bytes = fileClassLoader.getClassData(realClass);
                      messageClass = dynamicGameClassLoader.findClass(realClass, bytes);
                  } else {
                      //读取 game_server_handler.jar包所在位置
                      URL url = ClassLoader.getSystemClassLoader().getResource("./");
                      File file = new File(url.getPath());
                      File parentFile = new File(file.getParent());
                      String jarPath = parentFile.getPath() + File.separator + "lib/game_server_handler.jar";
                      logger.info("message load jar path:" + jarPath);
                      JarFile jarFile = new JarFile(new File(jarPath));
                      fileClassLoader.initJarPath(jarFile);
                      byte[] bytes = fileClassLoader.getClassData(realClass);
                      messageClass = dynamicGameClassLoader.findClass(realClass, bytes);
                  }
                  logger.info("handler load: " + messageClass);
  
                  IMessageHandler iMessageHandler = getMessageHandler(messageClass);
                  AbstractMessageHandler handler = (AbstractMessageHandler) iMessageHandler;
                  handler.init();
                  Method[] methods = messageClass.getMethods();
                  for (Method method : methods) {
                      if (method.isAnnotationPresent(MessageCommandAnnotation.class)) {
                          MessageCommandAnnotation messageCommandAnnotation = (MessageCommandAnnotation) method
                                  .getAnnotation(MessageCommandAnnotation.class);
                          if (messageCommandAnnotation != null) {
                              addHandler(messageCommandAnnotation.command(), iMessageHandler);
                          }
                      }
                  }
  
              }
          }
      } 
                              #location 22 
                              #vulnerability type NULL_DEREFERENCE