Adding CORS in HAPROXY 1.6.9 with rspadd headers - haproxy

Question

I have setup HAPROXY on top of Apache which is working fine but I am not able make api call from other domain, It was CORS issues so I added
rspadd Access-Control-Allow-Origin:\ *
But still it is not adding response headers in api call.
Please let me know. Is there any other way to achieve it?
Here is my whole haproxy.cfg file
global
log 127.0.0.1 local2
#log 127.0.0.1 local1 notice
#log loghost local0 info
#log /dev/log local0 info
log-tag haproxy
maxconn 4096
chroot /usr/share/haproxy
uid 99
gid 99
daemon
debug
#quiet
defaults
log global
mode http
option httplog
option dontlognull
retries 3
redispatch
maxconn 2000
contimeout 5000
clitimeout 5000
srvtimeout 5000
frontend https
#bind *:80
bind *:443 ssl crt /etc/ssl/certs/server.bundle.pem
option http-buffer-request
declare capture request len 400000
http-request capture req.body id 0
log-format {"%[capture.req.hdr(0)]"}
# /opt/causeway/etc/libwebsockets-cpa.pem
acl httpsapi path_beg /API
use_backend serv_https_api if httpsapi
default_backend default_apache
frontend http
bind *:80
#bind *:443 ssl crt /etc/ssl/certs/server.bundle.pem
acl api path_beg /api
use_backend serv_api if api
default_backend default_apache
backend default_apache
server apache 127.0.0.1:81
backend serv_api
server server1 127.0.0.1:7687
rspadd Access-Control-Allow-Origin:\ *
rspadd Access-Control-Max-Age:\ 31536000
backend serv_https_api
server server2 127.0.0.1:7687
rspadd Access-Control-Allow-Origin:\ *
rspadd Access-Control-Max-Age:\ 31536000
# mode tcp
# log global
# tcp-request inspect-delay 5s
# tcp-request content accept if { req.ssl_hello_type 1 }
Any help highly appriciated.