Restore EnumMemberAttribute for .net10

[vpetrusevici]

Summary

This PR updates the attribute pattern used for enum members across the project to ensure full compatibility with both System.Text.Json (specifically in .NET 9+) and Newtonsoft.Json.

Problem

Previously, enum members used a conditional #if NET9_0_OR_GREATER block with an #else clause that toggled between [JsonStringEnumMemberName] and [EnumMember].

#if NET9_0_OR_GREATER
    [JsonStringEnumMemberName("value")]
#else
    [EnumMember(Value = "value")]
#endif

While this worked for System.Text.Json, it broke compatibility with Newtonsoft.Json (and tools like NSwag that rely on it) when running on .NET 9+. Since Newtonsoft.Json does not recognize [JsonStringEnumMemberName], it would fall back to default naming, leading to serialization mismatches in environments where System.Text.Json is not the primary serializer.

Solution

The #else block has been removed, making [EnumMember] unconditional. [JsonStringEnumMemberName] remains wrapped in #if NET9_0_OR_GREATER to take advantage of native .NET 9 features while preserving the metadata needed by other libraries.

New Pattern:

#if NET9_0_OR_GREATER
    [JsonStringEnumMemberName("public-key")]
#endif
    [EnumMember(Value = "public-key")]
    PublicKey,

Key Changes

• Removed #else from enum member attributes in all model files.
• Ensured [EnumMember] is always present for every enum member.
• Maintained existing #if logic for JsonConverter declarations and internal logic where appropriate.
• Verified that these changes preserve correct serialization behavior in NSwag and other Newtonsoft.Json-dependent consumers.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 78.64%. Comparing base (1830c17) to head (f720524).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #655   +/-   ##
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  Coverage   78.64%   78.64%           
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  Files          98       98           
  Lines        2548     2548           
  Branches      425      425           
=======================================
  Hits         2004     2004           
  Misses        434      434           
  Partials      110      110           

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[vpetrusevici]

@abergs sorry, we need to restore this attribute :)
It's still needs for Newtonsoft.Json cases...

[abergs]

@vpetrusevici Have we verified that the original issue is still resolved when EnumMember is added?

And, is there a way to add tests to confirm the proper behavior in serialization?

[vpetrusevici]

Yes. I'll try to add test, including Newtonsoft

[vpetrusevici]

@vpetrusevici Have we verified that the original issue is still resolved when EnumMember is added?

And, is there a way to add tests to confirm the proper behavior in serialization?

tests added

[vpetrusevici]

@abergs anything else? :)

[abergs]

All good, preview.3 will be rolling out.

[vpetrusevici]

@abergs hi! did you release it?

[vpetrusevici]

@abergs, preview.3 is still unavailable :(

[abergs]

@vpetrusevici Seems there was a github issue while running tests. Running everything again.