WEBrick ignore bad host component - ruby

Question

Is there a way to ignore a bad host component in Webrick?
I'm running a Sinatra/Rack service on localhost:3000. This service registers with a service-facade service running also on localhost; the service-facade will assign a URL app-key.1:1111 which will get routed to my application on localhost:3000. Therefore allowing a client to be able to talk to my service via the service-facade without having to know the host+port of my service. The problem is, the service-facade uses the wrong HOST in the header (it uses the app-key.1 host+port instead of localhost:3000) and I'm told that the people who manage the service-facade that it is not easy to change this header.
To give some more detail, the service-facade is written as a Java application. It takes the headers from the request and just reforwards it to the resource-server. As a result, you might think that as long as the client talking to the service-facade uses the correct HOST in the host header, then everything would work; however, this defeats the purpose of the service-facade because the client needed to know the resource-server's host beforehand.
I can fix it if I somehow hook something in before any of this host check happens. The funny thing is, that for some reason, Tomcat seems to not care about this host check so our Java applications that use this service don't seem to run into this issue.
Is there a way to bypass this check in WEBrick? Or maybe I can add the hostname somehow so that WEBrick will accept as a valid host as well?
The check specifically is: Exception `URI::InvalidComponentError' at /Users/bliu/.rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/uri/generic.rb:605 - bad component(expected host component): api_key.1
def check_host(v)
return v unless v
if #opaque
raise InvalidURIError,
"can not set host with registry or opaque"
elsif parser.regexp[:HOST] !~ v
raise InvalidComponentError,
"bad component(expected host component): #{v}"
end
return true
end