[BUG] [csharp] Required properties not sorted in ctor

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
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Description

Using the csharp emitter the required properties should not get a default value and they must then come first in the ordering.

Currently, it does not order the constructor doc or parameters based on being required flag. Additionally, the required properties are given a default value in the constructor. This is present in existing generated code which have required properties and optional properties.

openapi-generator version

OpenAPI declaration file content or url

samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/Pet.cs

Generation Details

./bin/generate-samples.sh ./bin/configs/csharp-restsharp-net8-echo-api.yaml

Steps to reproduce

view the Pet.cs file ctor and param documentation

Related issues/PRs

Suggest a fix

Sort order should be done before the template generation for the readWriteVars. not sure where this logic is though.

Start by running ./bin/generate-samples.sh ./bin/configs/csharp-restsharp-net8-echo-api.yaml and inspect samples/client/echo_api/csharp/restsharp/net8/EchoApi/src/Org.OpenAPITools/Model/Pet.cs. Trace the readWriteVars ordering and template generation used for the constructor documentation and parameters. Done means required properties appear first and do not receive default values in the generated constructor.