[BUG] openapi-generator-maven-plugin version 5.0.0 does not work for OpenApi 3.0 yml-files

Description

I have a perfect OpenApi 3.0.1 yml-file. openapi-generator-maven-plugin v4.3.1 generates perfect code.
When changing the plugin version from 4.3.1 to 5.0.0 I get a syntax error. No other changes.

[INFO]
[INFO] --- openapi-generator-maven-plugin:5.0.0:generate (api) @ core-automation ---
[ERROR] failed to read resource listing
com.fasterxml.jackson.core.JsonParseException: Unrecognized token 'openapi': was expecting (JSON String, Number, Array, Object or token 'null', 'true' or 'false')
at [Source: (StringReader); line: 1, column: 8]

openapi-generator version

5.0.0

OpenAPI declaration file content or url

openapi: 3.0.1
info:
  title: my Title
  description: Documentation of my REST APIs.
  ...

Generation Details

mvn install

Steps to reproduce

mvn install

Related issues/PRs

N/A

Suggest a fix

???

Start with the openapi-generator-maven-plugin 5.0.0 generation entry point and reproduce the failure using the provided OpenAPI 3.0.1 YAML and mvn install. Compare the same generation with plugin version 4.3.1 to isolate the regression. Done means the unchanged YAML is accepted by 5.0.0 and code generation completes without the JSON parse error.