+ /// SCID/SCID Alias -> pending `update_add_htlc`s to decode.
+ ///
+ /// Note that because we may have an SCID Alias as the key we can have two entries per channel,
+ /// though in practice we probably won't be receiving HTLCs for a channel both via the alias
+ /// and via the classic SCID.
+ ///
+ /// Note that no consistency guarantees are made about the existence of a channel with the
+ /// `short_channel_id` here, nor the `channel_id` in `UpdateAddHTLC`!
+ ///
+ /// See `ChannelManager` struct-level documentation for lock order requirements.
+ decode_update_add_htlcs: Mutex<HashMap<u64, Vec<msgs::UpdateAddHTLC>>>,
+