Modifying headers before replaying request using Pact

spike.rb

class ProxyApp
  
  def initialize real_app
    @real_app = real_app
  end
  
  def call env
    @real_app.call(env.merge('HTTP_AUTHORIZATION' => '12345'))
  end
end

Pact.service_provider "Some Provider" do
  app do
    ProxyApp.new(RealApp)
  end
  
  honours_pact_with "Some Consumer" do
    #...
  end
end