More specific "derived" swagger type

overrideresourceproperties.json

{
    "swagger": "2.0",
    "info": {
        "title": "Examples of scenarios - #1, more constrained children",
        "version": "1.0"
    },
    "paths": [],
    "definitions": {
        "GenericResource": {
            "type": "object",
            "properties": {
                "location": {
                    "type": "string"
                },
                "properties": {
                    "additionalProperties": {},
                    "description": "The 'generic resource' has a well-known property 'properties' that is of type 'object'. Specific resource types can override it.",
                    "type": "object"
                }
            }
        },
        "VirtualMachineResource": {
            "description": "A specific resource types. Two things to pay attention to - the additionalProperties has to be specified (if this is an openapi 2.0 document), and the 'properties' property is more specific than what is in the 'GenericResource'",
            "allOf": [ { "$ref": "#/definitions/GenericResource" }],
            "additionalProperties": {},
            "properties": {
                "properties": {
                    "$ref": "#/definitions/VirtualMachineResourceProperties"
                }
            }
        },
        "VirtualMachineResourceProperties": {
            "type": "object",
            "properties": {
                "vmSize": {
                    "type": "string"
                }
            }
        }
    }
}