Could not load file or assembly 'Microsoft.OpenApi'... while using Swashbuckle.AspNetCore.Cli

I'm getting the subject error message while using the sample MS PowerShell script from the article Generating API clients using AutoRest when the following command line

dotnet swagger "tofile" --output "../../res/swagger.json" "../Sample.Api/bin/Debug/netcoreapp2.1/Sample.Api.dll" v1

is executed. Solution?

FYI: Swashbuckle.AspNetCore.Cli entry source code is located here: Swashbuckle.AspNetCore/src/Swashbuckle.AspNetCore.Cli/Program.cs