swagger UI is not showing anything in webapi

Turns out this line:

config.DependencyResolver = new StructureMapDependencyResolver(container);

in the question's class XyzWebApiStructureMapContainerConfigurator caused some issues.

Hope this helps someone in the future.

Had the same issue. Turns out the DI (Unity in my case) was configured to bind all loaded assemblies (one of which is Swashbuckle.Core).

Just a bit of refining which assemblies get binded has solved the issue:

var assemblies = AppDomain.CurrentDomain.GetAssemblies().Where(asm => asm.FullName.StartsWith("MySolution.MyProject"));

// Web API configuration and services
var container = new UnityContainer();
container.RegisterTypes(
    AllClasses.FromAssemblies(assemblies),
    WithMappings.FromMatchingInterface,
    WithName.Default);

config.DependencyResolver = new UnityDependencyResolver(container);