@type t() :: %Confuse.Fwup.Features{
  block_cache_size_mb: non_neg_integer() | nil,
  complete_fwup_version: Version.t(),
  delta_fwup_version: Version.t(),
  encrypted_deltas?: boolean(),
  encryption?: boolean(),
  fat_deltas?: boolean(),
  raw_deltas?: boolean(),
  specified_fwup_version: Version.t() | nil,
  valid?: boolean()
}