@seges/angular-language-picker/src/app/language-picker/interfaces/kendo.dropdown.interfaces.ts

For the time being the project scaffold expects TypeScript files.

export interface IKendoDropDownOptions<TDataSource> extends kendo.ui.DropDownListOptions {
    template?: (dataItem: TDataSource) => string;
    valueTemplate?: (dataItem: TDataSource) => string;
}