error will be set to contain the errors and FALSE will be returned.
WARNING: g_mount_unmount_finish has been deprecated since version 2.22 and should not be used in newly-written code. Use gMountUnmountWithOperationFinish instead.
gMountUnmountFinish(object, result, .errwarn = TRUE)objectGMount.resultGAsyncResult.TRUE if the mount was successfully unmounted. FALSE otherwise.errorGError location to store the error occuring, or NULL to
ignore.