[BUG] [ASPNETCORE] nullable array does not generate a nullable property

Bug Report Checklist

• [x ] Have you provided a full/minimal spec to reproduce the issue?
• [ x] Have you validated the input using an OpenAPI validator?
• [ x] Have you tested with the latest master to confirm the issue still exists?
• [ x] Have you searched for related issues/PRs?
• [ x] What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

Nullable arrays in OpenAPI Spec are not generated as nullable types

openapi-generator version

7.13.0

OpenAPI declaration file content

openapi: "3.0.0"
info:
  version: 1.0.0
  title: Swagger Petstore
servers: []
paths: {}
components:
  schemas:
    Pet:
      type: object
      properties:
        roleTypes:
          type: array
          items:
            type: string
          nullable: true

Generation Details

java -jar .\openapi-generator-cli.jar generate -i test.yaml -g aspnetcore -o ./tmp/ --additional-properties=useSwashbuckle=true --additional-properties=aspnetCoreVersion=5.0 --additional-properties=useNewtonsoft=false --additional-properties=buildTarget=library

Related issues/PRs

https://github.com/OpenAPITools/openapi-generator/issues/19516

Generated Code:

        [DataMember(Name="roleTypes", EmitDefaultValue=true)]
        public List<string> RoleTypes { get; set; }

expected outcome:

        [DataMember(Name="roleTypes", EmitDefaultValue=true)]
        public List<string>? RoleTypes { get; set; }

Start by reproducing the ASPNETCORE generation command with the provided test.yaml declaration and compare the generated RoleTypes property with the expected nullable form. Check the related issue 19516 for context. Done means the generated C# property for a nullable array includes the nullable marker while preserving the existing DataMember output.