Represents a local file.
path Local path to the locally available file part; may be empty.
canBeDownloaded True, if it is possible to try to download or generate the file.
canBeDeleted True, if the file can be deleted.
isDownloadingActive True, if the file is currently being downloaded (or a local copy is being generated by some other means).
isDownloadingCompleted True, if the local copy is fully available.
downloadOffset Download will be started from this offset. downloaded_prefix_size is calculated from this offset.
downloadedPrefixSize If is_downloading_completed is false, then only some prefix of the file starting from download_offset is ready to be read. downloaded_prefix_size is the size of that prefix.
downloadedSize Total downloaded file bytes. Should be used only for calculating download progress. The actual file size may be bigger, and some parts of it may contain garbage