Jenkins Eggplant Runner Plugin 0.0.1.301.v963cffe8ddb_8 and earlier sets the Java system property jdk.http.auth.tunneling.disabledSchemes to an empty value, disabling a protection mechanism of the Java runtime.
The product initializes or sets a resource with a default that is intended to be changed by the product’s installer, administrator, or maintainer, but the default is not secure.