required ignored for properties referencing definitions with allOf

Hi,

I've noticed what seems like a bug with the generated types when the required keyword is used in a property which references a definition using allOf

Here's an example schema:

{
  "title": "Example Schema",
  "type": "object",
  "properties": {
    "reference": {
      "allOf": [{ "$ref": "#/definitions/defined" }],
      "required": ["subproperty"]
    }
  },
  "definitions": {
    "defined": {
      "type": "object",
      "properties": {
        "subproperty": {
          "type": "integer"
        }
      }
    }
  },

  "additionalProperties": false
}

and the generated typings

export interface ExampleSchema {
  reference?: Defined;
}
export interface Defined {
  subproperty?: number;
  [k: string]: unknown;
}

I understand that the interface Defined is probably just pulled straight from the definitions section which is why the subproperty key is optional, but I would expect that the generated types would know that the Defined interface being used by ExampleSchema has subproperty as mandatory.

If you explore this in a json schema validator you will see that given the example schema above, this object:

{
   "reference": {
      "foo": "bar"
    }
}

is invalid since Required properties are missing from object: subproperty.

but with the current json-schema-to-typescript implementation,

const thing:ExampleSchema = {
   "reference": {
      "foo": "bar"
    }
}

is valid