The lifecycle of the app-instance ressource has changed with version 0.9.0. Previously they only exist, when a instance is running. Now they retain on stop. Therefore the
createdAt timestamp is the first-start. Additonally there is
lastStartedAt, which represents the last start.
In a future version (likely v0.10.0), the search-endpoint as well as relations in other endpoints can return app-instances, which are are not running. Currently only the running instances are returned like before. In order to handle the change you can already use the property