The feature's properties.id, otherwise its top-level id. This is the id the module's
getShown() and event handlers return. You can't combine it with index.
Optionalindex?: neverOptionalid?: neverThe feature's zero-based position in the collection that the module's getShown()
returns for it. If a module draws its features in several sources, each source counts
its own. You can't combine it with id.
Parameters to identify a shown feature by its ID or by its index.