用了egg框架，传给客户端的响应头首字母大写的问题!

Question

 this.ctx.set('Content-Type','application/json;charset=GB2312');

this.ctx.set('Content-Length',200);
this.ctx.set('devid','123456');
感觉这里设置没有效果，客户端接收的响应头就变成了

Vary: Origin
content-type: application/json; charset=utf-8
devid: 123456
x-frame-options: SAMEORIGIN
x-xss-protection: 1; mode=block
x-content-type-options: nosniff
x-download-options: noopen
x-readtime: 527
content-length: 30
Date: Wed, 09 Jun 2021 03:40:30 GMT
Connection: keep-alive
Keep-Alive: timeout=5

客户端他获取 Content-Type Content-Length 这2个就取不到。