Fields are not included in converted interface

[sashatrn]

I have Kotlin interface

interface HierarchicalCatalog : Catalog {
    var group: Boolean
    var parent: String
}

It is converted to Typescript as

export interface HierarchicalCatalog extends Catalog {
}

I expect it should be converted as

export interface HierarchicalCatalog extends Catalog {
    group: boolean;
    parent: string;
}