If a HTTP route assertion is used in policy with HTTP credentials specified AND a proxy is specified where the proxy does not require a user name and password, the requests will fail with the below error
Downstream service returned status (503). This is considered a failure case.
API Gateway 9.2
The following cluster-wide property will need to be added
CWP Name: io.httpEnableAutoChallenge
This is a hidden property that is editable by typing in its name in the Key field and then pressing [Tab]. (It cannot be located via the drop-down list.)
This property enables authentication to be handled automatically (HANDLE_AUTHENTICATION) by the underlying HTTP client. More details can be found here from the Apache page -> https://hc.apache.org/httpcomponents-client-ga/httpclient/apidocs/org/apache/http/client/params/ClientPNames.html