[REQ] typescript node should generate additional properties correctly

Created by: mosesonline

Is your feature request related to a problem? Please describe.

When an api decription has declared additional properties I cannot use the generated model for typescript-node.

Describe the solution you'd like

The generated model should have attributes with the type of the addional properties.

SomeClass :
      type: object
      properties:
        id:
          type: string
      additionalProperties:
        type: array
        items:
          type: string

=>

export class SomeClass {
    [key: string]: Array<string> | any;
    'id'?: string;

    static discriminator: string | undefined = undefined;

    static attributeTypeMap: Array<{name: string, baseName: string, type: string}> = [
        {
            "name": "id",
            "baseName": "id",
            "type": "string"
        }    ];

    static getAttributeTypeMap() {
        return SomeClass .attributeTypeMap;
    }
}

Describe alternatives you've considered

none

Additional context

none