[Python] Swagger 2.0 - 2.4.23 cannot generate allOf types

Description

I generate REST clients against swagger/openapi v2.0

• Using swagger-codegen-cli:2.4.8 we get a class "DataDaily" (see json below) with all attributes.
• Using 2.4.23 we only get the properties immediately under "DataDaily", not respecting the properties in "DataRef"

Swagger-codegen version

• Using 2.4.23
• This is a regression from version 2.4.8

Swagger declaration file content or url

    "DataDaily": {
      "allOf": [
        {
          "$ref": "#/definitions/DataRef"
        },
        {
          "type": "object",
          "required": [
            "timestamp",
            "asOfDate"
          ],
          "properties": {
            "seriesId": {
              "title": "seriesId",
              "type": "string"
            },
            "timestamp": {
              "type": "string",
              "format": "date-time"
            },
            "asOfDate": {
              "type": "string",
              "format": "date-time"
            }
          }
        }
      ]
    },

Command line used for generation

docker run --rm -v ${PWD}:/local swaggerapi/swagger-codegen-cli:2.4.23 generate -i http://internalserver/swagger/v2.0/swagger.json -l python -o /local -c /local/generate/config.json

config.json only contains information on package version.

Steps to reproduce

• Create a route returning an allOf type
• Generate Python client using command above

Related issues/PRs

Not that I could find.

Suggest a fix/enhancement

Previous behavior (e.g. 2.4.8) seemed reasonable.

Edit: I found the breakage occurs between 2.4.14 and 2.4.15

Use the provided Swagger v2.0 allOf declaration and Docker command to reproduce generation with swagger-codegen-cli 2.4.23, then compare it with 2.4.8 and the reported 2.4.14–2.4.15 boundary. Done means the generated Python client includes DataRef properties in DataDaily while retaining its direct properties.