Causing line: https://github.com/villadora/express-http-proxy/blob/5bada09cca1567cbb69a6ec3a637f6457f9e9495/app/steps/decorateUserResHeaders.js#L6 See [Node docs.](https://nodejs.org/api/deprecations.html#deprecations_dep0066_outgoingmessage_headers_outgoingmessage_headernames)
