[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

???

[stephanpelikan]

We had the same issue with the URL

/api/admin/v1

It worked for builds on a Linux machine but failed for builds on a Windows machine.

We changed the URL to

http://localhost/api/admin/v1

and now it works.

Two major questions:

1. Why there is no proper error message instead of Unrecognized token ‘openapi’?
2. Can the documentation be updated since there is no hint that “absolute URL” is different for Linux and Windows.

From the documentation:

url string REQUIRED. A URL to the target host. This URL supports Server Variables and MAY be relative, to indicate that the host location is relative to the location where the OpenAPI document is being served. Variable substitutions will be made when a variable is named in {brackets}.

[maarten-daalder-isaac]

Hi @stephanpelikan, regarding 1, the code assumes that if there is an error that it isn’t a YAML file and then tries the JSON variant. Which fails due to openapi not being { or other valid JSON token.

Regarding 2, once the upstream library is fixed and the plugin is updated the problem should go away. See also the comment by @wing328 above yours.