Get application by key

Retrieve an application by the application key. ### Expanding the application response LaunchDarkly supports expanding the "Get application" response to include additional fields. To expand the response, append the `expand` query parameter and include the following: * `flags` includes details on the flags that have been evaluated by the application For example, use `?expand=flags` to include the `flags` field in the response. By default, this field is **not** included in the response.