output: #fixed code
                                  public static List<Class<?>> getClasses(final String packageName) {
          List<Class<?>> classes = new LinkedList<Class<?>>();
  
          List<File> paths = getPackageDirectories(packageName);
  
          for (File path : paths) {
              for (File entry : path.listFiles()) {
                  if (isClass(entry.getName())) {
                      Class<?> clazz = getPathEntryAsClass(packageName, entry.getName());
                      classes.add(clazz);
                  }
              }
          }
  
          return classes;
      }
input: #vulnerable code 
                                  public static List<Class<?>> getClasses(final String packageName) {
          List<Class<?>> classes = new LinkedList<Class<?>>();
  
          File directory = getPackageAsDirectory(packageName);
  
          for (File entry : directory.listFiles()) {
              if (isClass(entry.getName())) {
                  Class<?> clazz = getPathEntryAsClass(packageName, entry.getName());
                  classes.add(clazz);
              }
          }
  
          return classes;
      } 
                              #location 6 
                              #vulnerability type NULL_DEREFERENCE