code: public <T extends OmiseObject> Map<String, Object> serializeToMap(T model) {
          return objectMapper.convertValue(model, new TypeReference<Map<String, Object>>() {
          });
      }
docs: Serialize the given model to a map with JSON-like structure.
  
  @param model The {@link OmiseObject} to serialize.
  @param <T>   The type of the model to serialize.
  @return The map containing the model's data.