@Retention(value=SOURCE)
public static @interface OfflineRegion.DownloadState
A region is either inactive (not downloading, but previously-downloaded
resources are available for use), or active (resources are being downloaded
or will be downloaded, if necessary, when network access is available).
This state is independent of whether or not the complete set of resources
is currently available for offline use. To check if that is the case, use
`OfflineRegionStatus.isComplete()`.