Background, this configuration --
- http://artifacts.org
server-a-1
- http://artifacts.org
server-a-2
- http://artifacts.org/ValueSet
server-b
- http://artifacts.org/Questionnaire
server-c
Given 'http://artifact.org/Questionnaire/abc' => try in order: server-c, server-a-1, server-a-2
Given 'http://artifact.org/ValueSet/abc' => try in order: server-b, server-a-1, server-a-2
Given 'http://artifact.org/PlanDefinition/abc' => try in order: server-a-1, then server-a-2