springfox: Inherited properties are duplicated

The polymorphism implemented in PR #1152 seems to not work correctly. Properties defined in the parent type are also present in the subtype but according to the oas 3.0 spec only additional properties should be in the subtype.

@ApiModel(subTypes = {Car.class})
class Vehicle {
	private String make;
}

@ApiModel(parent = Vehicle.class)
class Car extends Vehicle {
	private int seatingCapacity;
}

actual output:

{
  "Car": {
    "title": "Car",
    "allOf": [
      {
        "$ref": "#/definitions/Vehicle"
      },
      {
        "type": "object",
        "properties": {
          "make": {
            "type": "string"
          },
          "seatingCapacity": {
            "type": "integer",
            "format": "int32"
          }
        },
        "title": "Car"
      }
    ]
  }
}

expected output (without make property inherited from vehicle):

{
  "Car": {
    "title": "Car",
    "allOf": [
      {
        "$ref": "#/definitions/Vehicle"
      },
      {
        "type": "object",
        "properties": {
          "seatingCapacity": {
            "type": "integer",
            "format": "int32"
          }
        },
        "title": "Car"
      }
    ]
  }
}