$request input 获取参数null

$params = $request->input('params');

$params = null

isJson

Str::contains($this->header('CONTENT_TYPE'), ['/json', '+json']);

查看header 头
Content-Type:      application/x-www-form-urlencoded; charset=UTF-8
不是 json 结构

json 结构的如下
    Content-Type:      application/json;charset=UTF-8 

$params = json_decode($request->getContent(),true);