The swagger is not shown

[Agrippino]

Describe the bug
I can't reach the swagger that ocelot connects to. Upstream addresses work but swagger doesn't appear.

Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware[1]
An unhandled exception has occurred while executing the request.
System.ArgumentNullException: Value cannot be null. (Parameter 'source')
at System.Linq.ThrowHelper.ThrowArgumentNullException(ExceptionArgument argument)
at System.Linq.Enumerable.Cast[TResult](IEnumerable source)
at MMLib.SwaggerForOcelot.Transformation.SwaggerJsonTransformer.RemoveItems[T](JToken token, JToken paths, Func2[] searchPaths) at MMLib.SwaggerForOcelot.Transformation.SwaggerJsonTransformer.TransformSwagger(JObject swagger, IEnumerable1 routes, String hostOverride, SwaggerEndPointOptions endPointOptions)
at MMLib.SwaggerForOcelot.Transformation.SwaggerJsonTransformer.TransformSwaggerOrOpenApi(String swaggerJson, IEnumerable1 routes, String serverOverride, SwaggerEndPointOptions endPointOptions) at MMLib.SwaggerForOcelot.Transformation.SwaggerJsonTransformer.Transform(String swaggerJson, IEnumerable1 routes, String serverOverride, SwaggerEndPointOptions endPointOptions)
at MMLib.SwaggerForOcelot.Middleware.SwaggerForOcelotMiddleware.Invoke(HttpContext context, ISwaggerEndPointProvider swaggerEndPointRepository, IDownstreamSwaggerDocsRepository downstreamSwaggerDocs)
at Microsoft.AspNetCore.Builder.Extensions.MapMiddleware.InvokeCore(HttpContext context, PathString matchedPath, PathString remainingPath)
at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.MiddlewareAnalysis.AnalysisMiddleware.Invoke(HttpContext httpContext)
at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
at Microsoft.AspNetCore.MiddlewareAnalysis.AnalysisMiddleware.Invoke(HttpContext httpContext)
at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context)

This only happens with one solution, the other two go without problems.