NSwag.Commands net6.0 cannot find System.Text.Encodings.Web 8.0.0

[jnyrup]

I tried upgrading NSwag.Commands from 14.0.7 to 14.0.8 for a project running .net6 which then failed with the following exception:

Could not load file or assembly 'System.Text.Encodings.Web, Version=8.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51'. The system cannot find the file specified.

and this stack trace.

at NJsonSchema.CodeGeneration.DefaultTemplateFactory.LiquidParser..ctor()
at NJsonSchema.CodeGeneration.DefaultTemplateFactory.LiquidTemplate..cctor()

Minimal reproducible example

using NSwag.Commands.CodeGeneration;

var command = new OpenApiToCSharpClientCommand
{
    Input = "https://petstore.swagger.io/v2/swagger.json",
};

await command.RunAsync();

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net6.0</TargetFramework>
  </PropertyGroup>
	
  <ItemGroup>
    <PackageReference Include="NSwag.Commands" Version="14.0.8" />
  </ItemGroup>
</Project>

This is also reproducible by changing the TFM of NSwag.CodeGeneration.Tests from net8 to net6.

I traced this via #4913 back to sebastienros/fluid#639 which upgrade Fluid.Core from System.Text.Json 5.0.2 to 8.0.3 for the netstandard2.0 targets.

So the previously referenced Fluid.Core@2.5.0 references System.Text.Json@5.0.2, whereas the now referenced Fluid.Core@2.9.0 references System.Text.Json@8.0.3.

When looking in the generated project.assets.json for the example project above, for to me unknown reasons, it looks like it references Fluid.Core@net6, so it somehow isn't instructed to bump System.Text.Json to 8.0.3
I guess this is the underlying reason why NSwag.Commands doesn't "just work" for .net6.0.

Possible workarounds on my side:

• Upgrade to .net8
• Add <PackageReference Include="System.Text.Json" Version="8.0.3" />

Possible workaround in NSwag.CodeGeneration.csproj

• Add <PackageReference Include="System.Text.Json" Version="8.0.3" Condition="'$(TargetFramework)'=='netstandard2.0'" />