replace request.env['HTTP_HOST'] with request.host

request.env['HTTP_HOST'] doesn't respect X-Forwarded-Host,
whereas request.host does

Author: edvakf

lib/grape-swagger/endpoint.rb

@@ -24,7 +24,7 @@ def swagger_object(target_class, request, options)
         swagger:        '2.0',
         produces:       content_types_for(target_class),
         authorizations: options[:authorizations],
-        host:           GrapeSwagger::DocMethods::OptionalObject.build(:host, options, request.env['HTTP_HOST']),
+        host:           GrapeSwagger::DocMethods::OptionalObject.build(:host, options, request.host),
         basePath:       GrapeSwagger::DocMethods::OptionalObject.build(:base_path, options, request.env['SCRIPT_NAME']),
         tags:           GrapeSwagger::DocMethods::TagNameDescription.build(options),
         schemes:        options[:schemes].is_a?(String) ? [options[:schemes]] : options[:schemes]