Missing square brackets on object array property after serializing.

• OS: Windows
• Browser: Chrome
• Version: 113.0.5672.63
• Method of installation: PHP port for swagger UI - https://github.com/zircote/swagger-php
• Swagger-UI version:v4.18.3
• Swagger/OpenAPI version: 3.0

When using content-type as multi-part/form-data with array object parameters, it seems that swagger UI encodes the parameter incorrectly, its missing square brackets for arrays []:

Here is my open api definition, you can see the problem for yourself on https://editor-next.swagger.io just paste the definition and test the field.

openapi: 3.0.3
info:
  title: Swagger Petstore - OpenAPI 3.0
  description: 'test'
  version: "1.0.0"
  termsOfService: http://swagger.io/terms/
servers:
  - url: "https://127.0.0.1"
paths:
  /api/kits:
    post:
      tags:
      - Kit
      summary: Create a new kit
      description: Create a new kit
      operationId: createKit
      requestBody:
        description: Pass kit details
        required: true
        content:
          multipart/form-data:
            schema:
              properties:
                products:
                  type: array
                  items:
                    properties:
                      id:
                        type: integer
                        example: '1'
                      quantity:
                        type: integer
                        example: '1'
                    type: object
                name:
                  type: string
                  format: text
                  example: Kit 1
              type: object
      responses:
        '200':
          description: Successful operation

The array property is not serialized properly, its missing the square brackets...
Is this behavior intended, or is this a bug? How do I fix this?

Start by reproducing the report in Swagger UI or editor-next.swagger.io with the provided OpenAPI 3.0.3 multipart/form-data definition and inspect the request serialization path. Done means the object array property is serialized with the expected square brackets ([]) while preserving the other form fields.