Preview:
  public static void setData(Object object){
    for (Field field : object.getClass().getDeclaredFields()) {
      field.setAccessible(true);
      try {
        String value = String.valueOf(field.get(object));
        if ("null".equals(value)){
          field.set(object, "test");
        }
      } catch (Exception e) {
        throw new RuntimeException(e);
      }
    }
  }
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