[BUG] YAML reference is not supported in openapi 3.0.0

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

Reference & and * feature in YAML is not supported in openapi 3.0.0

openapi-generator version

<groupId>org.openapitools</groupId>
<artifactId>openapi-generator-maven-plugin</artifactId>
<version>3.3.4</version>

OpenAPI declaration file content or url

openapi: 3.0.0
info:
  version: 0.0.1
  title: AIML Feasture Ingestion Service
  termsOfService: http://swagger.io/terms/
servers:
  - url: https://petstore.swagger.io/v1

paths:
  /job_runs:
    post:
      tags:
        - job_runs
      summary: Trigger a NEW ingestion job run
      description: ""
      operationId: triggerJobRun
      requestBody:
        description: Request body that needs to trigger a job
        required: true
        content:
          application/json:
            schema:
              $ref: "#/components/schemas/JobRunRequest"
      responses:
        "404":
          description: Feasture set ID/version not found
        "200":
          description: Success
    

  /job_runs/{job_run_id}:
    get:
      tags:
        - job_runs
      summary: Get an ingestion job run
      description: ""
      parameters:
        - name: job_run_id
          in: path
          description: The ID of the job run
          schema:
            type: string
          required: true
      responses:
        "404":
          description: Job run ID not found
        "200":
          description: OK
          content:
            application/json:
              schema:
                $ref: "#/components/schemas/JobRunResponse"
components:
  schemas:
    JobRunRequest:
      type: object
      properties: &request_prop
        feature_set_id:
          type: string
        run_by:
          type: string
        correlation_id:
          type: string
      required:
        - feature_set_id
        - run_by
    JobRunResponse:
      type: object
      properties:
        <<: *request_prop
        state:
          type: string
          enum:
            - created
            - started
            - success
            - error
        error:
          type: string
          description: Error details for `error` state
        create_time:
          type: string
        start_time:
          type: string
        end_time:
          type: string
``

##### Generation Details

```log
[ERROR] 
org.openapitools.codegen.SpecValidationException: There were issues with the specification. The option can be disabled via validateSpec (Maven/Gradle) or --skip-validate-spec (CLI).
 | Error count: 1, Warning count: 0
Errors: 
	-attribute components.schemas.JobRunResponse.properties is not of type `object`

    at org.openapitools.codegen.config.CodegenConfigurator.toClientOptInput (CodegenConfigurator.java:569)
    at org.openapitools.codegen.plugin.CodeGenMojo.execute (CodeGenMojo.java:607)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:137)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
    at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:193)
    at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke (Method.java:498)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)

Steps to reproduce

1. create a mvn project with open-api plugin to generate java codes.
2. get the error in Generation Details

Related issues/PRs

Suggest a fix

Start by reproducing the supplied YAML declaration with the openapi-generator Maven plugin, following the validation failure at CodegenConfigurator. Trace how the components.schemas.JobRunResponse.properties value is parsed and validated; done means YAML anchors and merge keys are accepted in this OpenAPI 3.0.0 example and generation proceeds without the reported validation error.