public void setUpdateContentLength(boolean updateContentLength) {
        this.updateContentLength = updateContentLength;
    }
Whether to update the 'Content-Length' header of the response. When set
to {@code true}, the response is buffered in order to determine the
content length and set the 'Content-Length' header of the response.
<p>
The default setting is {@code false}.
src/main/java/com/alibaba/fastjson/support/spring/FastJsonJsonView.java