CORs on confluence with whitelist disabled

[Etsu]

Hello,

I am working on sending https requests through confluence to an external site. The responded to me with this error. as I am in testing mode, my whitelist is disabled, so it supposes to receive all incoming/outcoming requests. 

I am not sure what can I do to resolve this problem.

I appreciate any suggestions and help!

Error msg:

Failed to load {external url}: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:1990' is therefore not allowed access.