Update System.Text.Json 5.0.0 (transitive reference) -> 9.0.0 (direct…

[sliekens]

Discussion Reference

https://discord.com/channels/531175899588984842/599270434642460753/1307336003156971574

Is this a breaking change?

(AI generated)

Polymorphic Serialization: Polymorphism for object types with custom converters was disabled in .NET 7. All object values now rely on the custom converter, requiring explicit type specification for polymorphism.

Source Generator Behavior: Reflection fallback in source-generated serializers was removed, requiring explicit annotation for all serialized types.

JsonSerializerOptions Copying: Copying JsonSerializerOptions now preserves the JsonSerializerContext, affecting reuse scenarios.

Justification

Currently, System.Text.Json 5.0.0 is already present as a transitive dependency of Gw2Sharp, but this version is obsolete and missing newer features like polymorphic serialization, which is a feature I want to use in my module.

Rather than updating Gw2Sharp and then updating Blish HUD, it seems appropriate to me that Blish HUD should dictate which version of the library is available. It's not possible to choose a different version as a module author. (Gw2Sharp may continue to target >=5.0.0 for broadest compatibility, I don't think it is affected by the breaking changes above.)

I have made sure that Blish HUD still runs with this newer package version. However, existing modules that use System.Text.Json might be affected by the breaking changes. This is a general problem with the Blish module ecosystem, not specific to this change.

Also consider the performance improvements made to System.Text.Json in the last 4 major versions. This update should make Blish HUD somewhat more efficient.

[Taschenbuch]

A note on the performance aspect:
I read about it several years ago when system.text.json started to replace newtonsoft, so i might be wrong, but if i remember correctly system.text.json is only more performant by using spans which is a .NET and not a .NET Framework feature. so to get the full benefit we need to wait for blish to migrate to .NET.

[sliekens]

@Taschenbuch it's not exactly like that. Span types can be used in .NET Framework as a NuGet package: https://www.nuget.org/packages/System.Memory/#readme-body-tab, and this is what STJ uses.

However, it is true that the .NET Framework runtime does not use Span, so STJ is still going to be slower in .NET Framework than in .NET 9.