[BUG] [Typescript] Missing type

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?

Description

See examples below

openapi-generator version

From v4.3.0 to 5.0.0-SNAPSHOT

OpenAPI declaration file content or url

openapi: 3.0.0
info:
    title: datasources-v2-frontend
    version: 0.0.0
paths:
    '/{id}':
        patch:
            parameters:
                -
                    name: id
                    in: path
                    schema:
                        type: string
                    required: true
            responses:
                '200':
                    description: Ok
                    content:
                        application/json:
                            schema:
                                type: object
                                properties:
                                    data: {type: object, properties: {}}
                                required:
                                    - data
            tags:
                - Datasource
            requestBody:
                required: true
                content:
                    application/json:
                        schema:
                            $ref: '#/components/schemas/Partial_WorkerDatasourceVersion__'
            operationId: update-datasource
components:
    schemas:
        ApiOptions_:
            type: object
            properties:
                oauth:
                    type: string
                method:
                    oneOf:
                        -
                            type: string
                            enum:
                                - GET
                        -
                            type: string
                            enum:
                                - PATCH
                        -
                            type: string
                            enum:
                                - POST
                        -
                            type: string
                            enum:
                                - PUT
                body:
                    type: string
                headers:
                    type: object
                    properties: {}
                    additionalProperties:
                        type: string
                query:
                    type: object
                    properties: {}
                    additionalProperties:
                        type: string
                pagination:
                    oneOf:
                        -
                            type: object
                            properties:
                                type:
                                    type: string
                                    enum: [query]
                                value:
                                    type: string
                            required:
                                - type
                                - value
                        -
                            type: object
                            properties:
                                type:
                                    type: string
                                    enum: [hypermediaAttribute]
                                value:
                                    type: string
                            required:
                                - type
                                - value
        ApiOptions:
            $ref: '#/components/schemas/ApiOptions_'
        Partial_WorkerDatasourceVersion__:
            type: object
            properties:
                companyId:
                    type: string
                resourceGroupIds:
                    type: array
                    items:
                        type: string
                name:
                    type: string
                apiOptions:
                    $ref: '#/components/schemas/ApiOptions'

Generation Details

docker run --rm -v "${PWD}:/local" openapitools/openapi-generator-cli:v4.3.0 generate \
            --additional-properties=useSingleRequestParameter=true,enumPropertyNaming=UPPERCASE \
            -i /local/swagger.yaml \
            -g typescript-axios \
            -o /local/client

Generated typescript:

/**
 * 
 * @export
 * @interface PartialWorkerDatasourceVersion
 */
export interface PartialWorkerDatasourceVersion {
    /**
     * 
     * @type {string}
     * @memberof PartialWorkerDatasourceVersion
     */
    companyId?: string;
    /**
     * 
     * @type {Array<string>}
     * @memberof PartialWorkerDatasourceVersion
     */
    resourceGroupIds?: Array<string>;
    /**
     * 
     * @type {string}
     * @memberof PartialWorkerDatasourceVersion
     */
    name?: string;
    /**
     * 
     * @type {ApiOptions}
     * @memberof PartialWorkerDatasourceVersion
     */
    apiOptions?: ApiOptions;
}

The type ApiOptions is never defined. Probably because the ApiOptions ref to ApiOptions with an underscore and the underscore gets removed by the generator leading to this bug.

Reproduce the issue with the supplied OpenAPI declaration and the docker command using the typescript-axios generator. Trace how the ApiOptions_ schema and its ApiOptions alias are named during generation; done means the generated TypeScript declares ApiOptions and the PartialWorkerDatasourceVersion reference resolves correctly.