Minor A valid servers block in an OAS spec containing an empty variables declaration with cause the import to fail:
"servers": [ { "url": "https://example.production.gw.apicast.io:443", "variables": {} } ],
{:exception=>{:class=>NoMethodError, :message=>"undefined method `map' for nil:NilClass", :backtrace=>["/opt/system/app/lib/three_scale/open_api/url_resolver.rb:23:in `resolve_servers_from_variables'", "/opt/system/app/lib/three_scale/open_api/url_resolver.rb:27:in `resolve_servers_from_variables'", "/opt/system/app/lib/three_scale/open_api/url_resolver.rb:16:in `block in servers'", "/opt/system/app/lib/three_scale/open_api/url_resolver.rb:13:in `map'"]}, :parameters=>{}}
