Nginx请求头返回问题

开发需求curl www.xxx.com返回请求，结果得不到请求头

upstream client {
        server 172.16.148.115:8080 max_fails=0 fail_timeout=10s;
}
server {
        listen       80;
        server_name  www.xxx.com;
        underscores_in_headers on;
        access_log /data/nginx/logs/client/client_access.log;
        error_log /data/nginx/logs/client/client_error.log;
        
        location / {
			proxy_connect_timeout 75;            
			proxy_read_timeout 300;            
			proxy_send_timeout 300;            
			proxy_buffer_size 64k;            
			proxy_buffers   4 64k;
            proxy_busy_buffers_size 128k;
            proxy_temp_file_write_size 128k;
            proxy_pass http://client;
            proxy_http_version 1.1;
            proxy_set_header Connection "";
        } 
}
1：跨域问题（没有解决）
#add_header Access-Control-Allow-Origin *; 
#add_header Access-Control-Allow-Methods 'GET, POST, OPTIONS'; 
#add_header Access-Control-Allow-Headers 'DNT,X-Mx-ReqToken,Keep-Alive,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Authorization';
2:设定自定义请求头（没有解决）
#proxy_set_header用于
3：underscores_in_headers on;用于开启请求头key支持下划线'_'特殊符号，默认为off（解决！）
#underscores_in_headers on;

最后修改如下：

upstream client {
        server 172.116.148.115:8080 max_fails=0 fail_timeout=10s;
}
server {
        listen       80;
        server_name  www.xxx.com;
        underscores_in_headers on;
        access_log /data/nginx/logs/client/client_access.log;
        error_log /data/nginx/logs/client/client_error.log;
        
        location / {
			proxy_connect_timeout 75;            
			proxy_read_timeout 300;            
			proxy_send_timeout 300;            
			proxy_buffer_size 64k;            
			proxy_buffers   4 64k;
            proxy_busy_buffers_size 128k;
            proxy_temp_file_write_size 128k;
            proxy_pass http://client;
            proxy_http_version 1.1;
            proxy_set_header Connection "";
        } 
}