We have some middlewares before the proxy middleware to handle setting cookies (like authentication and others).
We set cookies like this in previous middlewares: res.cookie('name', 'value').

Responses that are proxies do not contain these Set-Cookie headers though. Other headers seem to pass fine.

We do not use userResHeaderDecorator.

express-http-proxy should not remove any Set-Cookie headers that have already been set on the response object.