[BUG] OpenAPI Generator fails to generate array models

Created by: segevfiner

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

OpenAPI generator fails to generate array models. It complains with:

[main] INFO  o.o.codegen.DefaultGenerator - Model {} not generated since it's an alias to array (without property) and `generateAliasAsModel` is set to false (default)

openapi-generator version

v4.3.1

And also tried latest master using Docker 07c23f4d.

OpenAPI declaration file content or url

openapi: '3.0.3'

info:
  title: Test
  version: 0.1.0

paths: {}

components:
  schemas:
    Test:
      type: array
      items:
        type: object
        properties:
          foo:
            type: string

Generation Details

docker run --rm \                                
  -v ${PWD}:/local openapitools/openapi-generator-cli generate \    
  -i /local/openapi.yaml \ 
  -g go \
  -o /local/out/go

Steps to reproduce

Generate a client for any language using the provided schema. Note that the array model is not generated with the log message from this bug's description.

Related issues/PRs

Suggest a fix

The following code is erroneous. An array has items not properties (Even required by the OpenAPI spec). You might need to cast Schema to ArraySchema to get access to items or something like that. https://github.com/OpenAPITools/openapi-generator/blob/41851b45e1f1ffa7f0df36270a6b3c0cee6425bb/modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultGenerator.java#L485-L488