rename method
Renames this file system entity.
Returns a Future<FileSystemEntity>
that completes with a
FileSystemEntity instance for the renamed file system entity.
If newPath
identifies an existing entity of the same type, that entity
is replaced. If newPath
identifies an existing entity of a different
type, the operation fails and the future completes with an exception.
Implementation
Future<FileSystemEntity> rename(String newPath);