public <T> T toObject(Class<T> clazz) {
        if (getFirstSourceText() == null) {
            return null;
        }
        return JSON.parseObject(getFirstSourceText(), clazz);
    }
remove padding for JSONP
@param padding padding
@return json after padding removed
webmagic-core/src/main/java/us/codecraft/webmagic/selector/Json.java