var bld = WebApplication.CreateBuilder();
bld.Services
   .AddFastEndpoints()
   .SwaggerDocument(o =>
   {
       o.DocumentSettings = s =>
       {
           s.DocumentName = "Initial Release";
           s.Version = "v0";
       };
   })
   .SwaggerDocument(o =>
   {
       o.MaxEndpointVersion = 1;
       o.ShowDeprecatedOps = true; // specify to show deprecated versions
       o.DocumentSettings = s =>
       {
           s.DocumentName = "Release 1";
           s.Version = "v1";
       };
   })
   .SwaggerDocument(o =>
   {
       o.MaxEndpointVersion = 2;
       o.ShowDeprecatedOps = true; // specify to show deprecated versions
       o.DocumentSettings = s =>
       {
           s.DocumentName = "Release 2";
           s.Version = "v2";
       };
   });

var app = bld.Build();
app
   .UseFastEndpoints()
   .UseSwaggerGen();
app.Run();

class MyEndpoint : EndpointWithoutRequest
{
    public override void Configure()
    {
        Get("say-hello");
        AllowAnonymous();
        Version(0, deprecateAt: 1); // specify when to deprecate
    }

    public override Task HandleAsync(CancellationToken c)
        => SendAsync($"hello from version: {Definition.Version.Current}");
}

class MyEndpoint_V1 : MyEndpoint
{
    public override void Configure()
    {
        base.Configure();
        Version(1, deprecateAt: 2); // specify when to deprecate
    }
}

class MyEndpoint_V2 : MyEndpoint
{
    public override void Configure()
    {
        base.Configure();
        Version(2); // latest version doesn't need to specify deprecation
    }
}