Add ibc fee docs

Author: chipshort

packages/std/src/ibc.rs

@@ -75,13 +75,52 @@ pub enum IbcMsg {
     /// This will close an existing channel that is owned by this contract.
     /// Port is auto-assigned to the contract's IBC port
     CloseChannel { channel_id: String },
+    /// Incentivizes the next IBC packet sent after this message with a fee.
+    /// Note that this does not necessarily have to be a packet sent by this contract.
+    /// The fees are taken from the contract's balance immediately and locked until the packet is handled.
+    ///
+    /// # Example
+    ///
+    /// Most commonly, you will attach this message to a response right before sending a packet using
+    /// [`IbcMsg::SendPacket`] or [`IbcMsg::Transfer`].
+    ///
+    /// ```rust
+    /// # use cosmwasm_std::{IbcMsg, IbcEndpoint, IbcFee, IbcTimeout, Coin, CosmosMsg, Response, Timestamp};
+    ///
+    /// let incentivize = IbcMsg::PayPacketFee {
+    ///     src: IbcEndpoint {
+    ///         port_id: "transfer".to_string(),
+    ///         channel_id: "source-channel".to_string(),
+    ///     },
+    ///     fee: IbcFee {
+    ///         recv_fee: vec![Coin::new(100u32, "token")],
+    ///         ..IbcFee::default()
+    ///     },
+    ///     relayers: vec![],
+    /// };
+    /// let transfer = IbcMsg::Transfer {
+    ///     channel_id: "source-channel".to_string(),
+    ///     to_address: "receiver".to_string(),
+    ///     amount: Coin::new(100u32, "token"),
+    ///     timeout: IbcTimeout::with_timestamp(Timestamp::from_nanos(0)),
+    ///     memo: None,
+    /// };
+    ///
+    /// # #[cfg(feature = "stargate")]
+    /// let _: Response = Response::new()
+    ///     .add_message(CosmosMsg::Ibc(incentivize))
+    ///     .add_message(CosmosMsg::Ibc(transfer));
+    /// ```
     PayPacketFee {
         src: IbcEndpoint,
         fee: IbcFee,
         /// Allowlist of relayer addresses that can receive the fee.
         /// This is currently not implemented and *must* be empty.
         relayers: Vec<String>,
     },
+    /// Incentivizes the existing IBC packet with the given port, channel and sequence with a fee.
+    /// Note that this does not necessarily have to be a packet sent by this contract.
+    /// The fees are taken from the contract's balance immediately and locked until the packet is handled.
     PayPacketFeeAsync {
         src: IbcEndpoint,
         sequence: u64,
@@ -92,7 +131,7 @@ pub enum IbcMsg {
     },
 }
 
-#[derive(Serialize, Deserialize, Clone, Debug, PartialEq, Eq, JsonSchema)]
+#[derive(Serialize, Deserialize, Default, Clone, Debug, PartialEq, Eq, JsonSchema)]
 pub struct IbcFee {
     // the packet receive fee
     pub recv_fee: Vec<Coin>,

packages/std/src/lib.rs

@@ -70,7 +70,7 @@ pub use crate::ibc::IbcChannelOpenResponse;
 pub use crate::ibc::{
     Ibc3ChannelOpenResponse, IbcAckCallbackMsg, IbcAcknowledgement, IbcBasicResponse,
     IbcCallbackRequest, IbcChannel, IbcChannelCloseMsg, IbcChannelConnectMsg, IbcChannelOpenMsg,
-    IbcDestinationCallbackMsg, IbcDstCallback, IbcEndpoint, IbcMsg, IbcOrder, IbcPacket,
+    IbcDestinationCallbackMsg, IbcDstCallback, IbcEndpoint, IbcFee, IbcMsg, IbcOrder, IbcPacket,
     IbcPacketAckMsg, IbcPacketReceiveMsg, IbcPacketTimeoutMsg, IbcReceiveResponse,
     IbcSourceCallbackMsg, IbcSrcCallback, IbcTimeout, IbcTimeoutBlock, IbcTimeoutCallbackMsg,
     TransferMsgBuilder,