+ /// The `channel_keys_id` for the channel which this output came from.
+ ///
+ /// For channels which were generated on LDK 0.0.119 or later, this is the value which was
+ /// passed to the [`SignerProvider::get_destination_script`] call which provided this
+ /// output script.
+ ///
+ /// For channels which were generated prior to LDK 0.0.119, no such argument existed,
+ /// however this field may still be filled in if such data is available.
+ channel_keys_id: Option<[u8; 32]>