[BUG] openapi-yaml template helper incorrectly converts unbounded-type array to arrays of objects.

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

When the input schema contains an array with no specific type, it gets converted to an array of objects. Which does not have the same meaning at all.

https://swagger.io/docs/specification/data-models/data-types/#array

An array of arbitrary types can be defined as:

openapi-generator version

openapi-generator-cli 5.0.0-SNAPSHOT

OpenAPI declaration file content or url

openapi: 3.0.0
info:
  title: api
  version: 1.0.1
servers:
  - url: /api/v1
    description: ''
tags:
  - name: General
    description: General commands
  - name: Configuration
    description: Configuration commands
paths:
  /test:
    get:
      summary: Your GET endpoint
      tags: []
      responses:
        '200':
          description: OK
      operationId: getTest
      requestBody:
        content:
          application/json:
            schema:
              $ref: ../core/model/definitions/TestObject.v1.json
components:
  schemas: {}

TestObject.v1.json:

{
  "title": "TestObject",
  "type": "object",
  "properties": {
    "something": {
      "type": "array",
      "items": {}
    }
  }
}

Generation Details

openapitools/openapi-generator-cli generate -i /local/api/api.yaml -t /local/core/swagger/mustache/nodejs-express-server/ -g nodejs-express-server -o /local/server/

Generated schema:

openapi: 3.0.0
info:
  title: api
  version: 1.0.1
servers:
- url: /api/v1
tags:
- description: General commands
  name: General
- description: Configuration commands
  name: Configuration
paths:
  /test:
    get:
      operationId: getTest
      requestBody:
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/TestObject'
      responses:
        "200":
          description: OK
      summary: Your GET endpoint
      tags: []
      x-eov-operation-handler: controllers/DefaultController
components:
  schemas:
    TestObject:
      example:
        something:
        - '{}'
        - '{}'
      properties:
        something:
          items:
            type: object
          type: array
      title: TestObject
      type: object

Notice this section:

something:
          items:
            type: object
          type: array

It converted my array of generic into an array of object

Start with the nodejs-express-server template at /local/core/swagger/mustache/nodejs-express-server/ and reproduce the output using the supplied OpenAPI and TestObject.v1.json files. Compare how the template handles array items defined as an empty schema. Done means an unbounded array remains generic rather than being emitted with items of type object.