[BUG] C#: `const` properties emit invalid `public const T X { get; } = ...` with auto-implemented properties

[dl-ezo]

Description

When generating C# models for a property declared with const in the schema, the C# generator with auto-implemented properties enabled (autoImplementedProperties: true, e.g. the --csharpAutoImplement CLI flag, commonly combined with --csharpNewtonsoft) renders an invalid property declaration that does not compile:

public const string EventType { get; } = "OnEntryStarted";

A C# const field cannot have property accessors ({ get; }). This is a compile error (e.g. CS0107/syntax error) — a const is a field, not a property.

This is a separate problem from the read-only assignment issue tracked in #2589, but both must be fixed for const properties to compile under the Newtonsoft preset (see "Related" below).

How to reproduce

import { CSharpGenerator } from '@asyncapi/modelina';

const generator = new CSharpGenerator({ autoImplementedProperties: true });

const schema = {
  $id: 'Event',
  type: 'object',
  properties: { eventType: { type: 'string', const: 'OnEntryStarted' } },
  required: ['eventType'],
};

const models = await generator.generate(schema);
for (const m of models) console.log(m.result);

CLI equivalent:

asyncapi generate models csharp ./event.yaml -o ./out --namespace MyNs --csharpAutoImplement --csharpNewtonsoft

Generated output — does not compile

public partial class Event
{
  public const string EventType { get; } = "OnEntryStarted";
}

Expected behavior

A const property should be rendered as a plain const field (matching what the record renderer already produces):

public const string EventType = "OnEntryStarted";

Root cause

In src/generators/csharp/renderers/ClassRenderer.ts, the auto-implemented-properties branch of the property preset emits the const declaration with { ${getter} } accessors. The record preset (RecordRenderer.ts) already renders the same case correctly without accessors.

Related

• C#: Newtonsoft serializer preset emits non-compiling ReadJson for const properties (assigns to getter-only property → CS0200) #2589 — Newtonsoft ReadJson assigns to the (read-only) const property → CS0200/CS0131. Even after fixing this declaration bug, the Newtonsoft converter still emits a non-compiling assignment, so both need to be addressed for --csharpNewtonsoft + const output to compile.

Environment

• Modelina: 5.10.1

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