[BUG][CSharp] constructor does not initialize enum properties when ConditionalSerialization=true, though they are in the parameters

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?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

When one runs the openapi-generator-cli 2.7.0-2.10.0 against a swagger.json to make a csharp client with the argument conditionalSerialization=true, the generated model class's constructor does not initialize any enum properties, though they are present in the constructor parameters, and the arguments for them are passed by the calling code.

Constructor that is output is:

        public TestModel(string text = default(string), SomeEnumEnum? someEnum = SomeEnumEnum.NUMBER_1)
        {
            this._Text = text;
            if (this.Text != null)
            {
                this._flagText = true;
            }
        }

Expected result is:

        public TestModel(string text = default(string), SomeEnumEnum? someEnum = SomeEnumEnum.NUMBER_1)
        {
            this._Text = text;
            if (this.Text != null)
            {
                this._flagText = true;
            }
            this._someEnum = someEnum;
            if (this.SomeEnum != null)
            {
                this._flagSomeEnum = true;
            }
        }

This doesn't happen when conditionalSerialization=false; at that point, the enum is initialized properly just as expected.

openapi-generator version

CLI version:

2.7.0 - 2.10.0 (don't know if it affects earlier versions)

OpenAPI declaration file content or url

{
    "openapi": "3.0.1",
    "info": {
        "title": "test functions",
        "description": "test functions",
        "version": "1.0.0"
    },
    "servers": [
        {
            "url": "http://localhost:7204/api"
        }
    ],
    "paths": {
        "/Function2": {
            "get": {
                "operationId": "function 2",
                "requestBody": {
                    "content": {
                        "application/json": {
                            "schema": {
                                "$ref": "#/components/schemas/testModel"
                            }
                        }
                    },
                    "required": true
                },
                "responses": {
                    "200": {
                        "description": "Payload of TestModel",
                        "content": {
                            "application/json": {
                                "schema": {
                                    "$ref": "#/components/schemas/testModel"
                                }
                            }
                        }
                    }
                }
            }
        }
    },
    "components": {
        "schemas": {
            "testModel": {
                "type": "object",
                "properties": {
                    "text": {
                        "type": "string",
                        "description": "Nullable Text",
                        "nullable": true
                    },
                    "someEnum": {
                        "enum": [
                            1,
                            2
                        ],
                        "type": "integer",
                        "format": "int32",
                        "default": 1
                    }
                }
            }
        }
    }
}

Start by locating the C# generator code that handles conditionalSerialization and constructor generation, then reproduce the issue with the supplied OpenAPI schema and compare it with conditionalSerialization=false. Done means generated constructors assign enum parameters and set their conditional flags, with regression coverage for the supplied model.