Sample Episerver initialization module to fix Web API 2 attribute routing if other code has already called GlobalConfiguration.Configure without calling MapHttpAttributes().

FixWebApiInitializationModule.cs

using System.Web.Http;
using EPiServer.Framework;
using EPiServer.Framework.Initialization;

namespace AlloyFindWithWebApi.Business.Initialization
{
    [InitializableModule]
    [ModuleDependency(typeof(FrameworkAspNetInitialization))]
    public class FixWebApiInitializationModule : IInitializableModule
    {
        public void Initialize(InitializationEngine context)
        {
            // register web api attributeroutes here
            // this module is executed before EPiServer.Marketing.Testing initialization module because that module
            // has dependency to EPiServer.Web.InitializationModule and this module uses FrameworkAspNetInitialization
            // which is executed before the InitializationModule
            // this is only needed in old marketing testing versions, issue has been fixed in version 2.5.11 at least
            GlobalConfiguration.Configure(config =>
            {
                config.MapHttpAttributeRoutes();
            });
        }

        public void Uninitialize(InitializationEngine context)
        {
        }
    }
}