Describe the bug
Explicitly specifying request body properties by putting @Content(schemaProperties=...) in a method-level @RequestBody doesn't cause the properties to be included in the generated schema.

To Reproduce

• Spring Boot 2.6.7
• Springdoc-openapi 1.6.8
• Modules: kotlin, security, ui (and their transitive dependencies)

@RestController
class ExampleController {
  @PostMapping("/upload", consumes = [MediaType.MULTIPART_FORM_DATA_VALUE])
  @RequestBody(content = [
        Content(
            schema = Schema(type = "object", requiredProperties = ["file"]),
            schemaProperties = [
                    SchemaProperty(name = "file", schema = Schema(type = "string", format = "binary"))],
            encoding = [Encoding(name = "file", contentType = "text/csv")])],
  )
  fun uploadCsv(request: HttpServletRequest): String {
    return "OK"
  }
}

Expected behavior
The above code should result in the following (leaving off the responses section for brevity):

  /upload:
    post:
      tags:
      - example-controller
      operationId: uploadCsv
      requestBody:
        content:
          multipart/form-data:
            schema:
              required:
              - file
              type: object
              properties:
                file:
                  type: string
                  format: binary
            encoding:
              file:
                contentType: text/csv

The actual output is missing the properties section of the schema:

  /upload:
    post:
      tags:
      - example-controller
      operationId: uploadCsv
      requestBody:
        content:
          multipart/form-data:
            schema:
              required:
              - file
              type: object
            encoding:
              file:
                contentType: text/csv

Additional context
I'm not using a FilePart or a RequestPart parameter here because the uploaded files are machine-generated output and can be multiple gigabytes in size. Spring (or Jetty) reads the entire request body from the client before calling the controller method if you declare one of those parameters. Instead I'm using Apache FileUpload to stream the contents of the file into my application code as it arrives from the client, but I want the API schema to be identical to what it would look like if I were using FilePart.