Setting servers to nil still fails validation

[pbdeuchler]

When using the chi-middleware validator setting swagger.Servers = nil will fail every request.

This can be reproduced by starting a server that correctly validates hostnames (i.e. not setting swagger.Servers to nil) and properly handles requests, and then setting swagger.Servers = nil. All requests will fail.

Here is the snippet of code that works as expected:

// Versions of our API to serve
v010123Handler := v010123def.NewStrictHandler(
	// Build service interface (business logic impl)
	v010123service.NewAPI(highPrioritySQS, normalPrioritySQS),
	[]v010123def.StrictMiddlewareFunc{},
)

// Get Swagger defininition for previous version
swagger, err := v010123def.GetSwagger()
if err != nil {
	panic(fmt.Errorf("Failed to get swagger for version 010123: %w", err))
}


// swagger.Servers = nil

// This holds the various versioned API routers
handlers := map[string]http.Handler{
	"010123": v010123def.HandlerWithOptions(v010123Handler, v010123def.ChiServerOptions{
		Middlewares: []v010123def.MiddlewareFunc{
			middleware.OapiRequestValidator(swagger),
		},
	}),
}

Then, changing nothing but uncommenting out // swagger.Servers = nil will cause the server to always fail requests.

I'm having difficulty finding exactly where the bug is, as it's difficult to inject debugging code kin-openapi libraries, but everything seems to be pointing to a similar issue here: getkin/kin-openapi#740, which also found regressions in this code getkin/kin-openapi#705.

I will be bringing this up with the kin-openapi project as well, but given there were recent changes in this project around swagger.Servers being nil I wanted to ensure that the issue was filed here first.