[BUG] [dart-dio] _id is generated as id

Created by: flodaniel

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

When generating a model a property _id is transformed and becomes id in the resulting dart class. In the provided example this breaks the class as it already has another id property.

I tested this on latest master with this command (hosting the yml on a public gist):

docker run --rm -v "${PWD}:/local" openapitools/openapi-generator-cli generate \
        -i https://gist.githubusercontent.com/flodaniel/65ffdf1e803773606dc42dccd58ba021/raw/7ce9e4e7721e1df9bb28c7d2de94581351f387ad/gistfile1.txt -g dart-dio -o /local/out/bad_id_generation

openapi-generator version

openapi-generator-cli 6.2.1 commit : b0ce532b built : 2022-11-01T09:40:00Z source : https://github.com/openapitools/openapi-generator docs : https://openapi-generator.tech/

OpenAPI declaration file content or url

https://gist.github.com/flodaniel/65ffdf1e803773606dc42dccd58ba021

openapi: 3.0.0
info:
  title: Bad _id generation
  version: 0.0.1
paths: {}
tags: []
servers: []
components: 
  schemas:
    ConflictingIdProperty:
      type: object
      properties:
        id:
          type: string
        _id:
          type: string

Generation Details

openapi-generator generate -i ./bad_id_generation.yml -g dart-dio -o ./bad_id_generation

Steps to reproduce

Run the generation
review the resulting conflicting_id_property.dart file with the conflicting id properties.

Related issues/PRs

Suggest a fix

The issue is probably within class.mustache (https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/dart/libraries/dio/serialization/built_value/class.mustache). baseName is correct but name is missing the _.