refactor: adapting transfer metadata bytes field to memo string (cosm…

…os#2595)

* adapting transfer metadata bytes field to memo string

* updating changelog

CHANGELOG.md

@@ -108,7 +108,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 * (apps/27-interchain-accounts) [\#2147](https://github.com/cosmos/ibc-go/pull/2147) Adding a `SubmitTx` gRPC endpoint for the ICS27 Controller module which allows owners of interchain accounts to submit transactions. This replaces the previously existing need for authentication modules to implement this standard functionality.
 * (testing/simapp) [\#2190](https://github.com/cosmos/ibc-go/pull/2190) Adding the new `x/group` cosmos-sdk module to simapp.
-* (apps/transfer) [\#2305](https://github.com/cosmos/ibc-go/pull/2305) Added optional metadata field to `FungibleTokenPacketData` and `MsgTransfer`.
+* (apps/transfer) [\#2595](https://github.com/cosmos/ibc-go/pull/2595) Adding optional memo field to `FungibleTokenPacketData` and `MsgTransfer`.
 
 ### Bug Fixes
 

docs/ibc/proto-docs.md

@@ -2255,7 +2255,7 @@ https://github.com/cosmos/ibc/tree/master/spec/app/ics-020-fungible-token-transf
 | `receiver` | [string](#string) |  | the recipient address on the destination chain |
 | `timeout_height` | [ibc.core.client.v1.Height](#ibc.core.client.v1.Height) |  | Timeout height relative to the current block height. The timeout is disabled when set to 0. |
 | `timeout_timestamp` | [uint64](#uint64) |  | Timeout timestamp in absolute nanoseconds since unix epoch. The timeout is disabled when set to 0. |
-| `metadata` | [bytes](#bytes) |  | optional metadata |
+| `memo` | [string](#string) |  | optional memo |
 
 
 
@@ -2317,7 +2317,7 @@ https://github.com/cosmos/ibc/tree/master/spec/app/ics-020-fungible-token-transf
 | `amount` | [string](#string) |  | the token amount to be transferred |
 | `sender` | [string](#string) |  | the sender address |
 | `receiver` | [string](#string) |  | the recipient address on the destination chain |
-| `metadata` | [bytes](#bytes) |  | optional metadata |
+| `memo` | [string](#string) |  | optional memo |
 
 
 

go.mod

@@ -43,7 +43,7 @@ require (
 	github.com/bgentry/go-netrc v0.0.0-20140422174119-9fd32a8b3d3d // indirect
 	github.com/bgentry/speakeasy v0.1.0 // indirect
 	github.com/btcsuite/btcd v0.22.1 // indirect
-	github.com/cenkalti/backoff/v4 v4.1.3 // indirect
+	github.com/cenkalti/backoff/v4 v4.1.1 // indirect
 	github.com/cespare/xxhash v1.1.0 // indirect
 	github.com/cespare/xxhash/v2 v2.1.2 // indirect
 	github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e // indirect

go.sum

@@ -180,9 +180,8 @@ github.com/c-bata/go-prompt v0.2.2/go.mod h1:VzqtzE2ksDBcdln8G7mk2RX9QyGjH+OVqOC
 github.com/casbin/casbin/v2 v2.1.2/go.mod h1:YcPU1XXisHhLzuxH9coDNf2FbKpjGlbCg3n9yuLkIJQ=
 github.com/cenkalti/backoff v2.2.1+incompatible h1:tNowT99t7UNflLxfYYSlKYsBpXdEet03Pg2g16Swow4=
 github.com/cenkalti/backoff v2.2.1+incompatible/go.mod h1:90ReRw6GdpyfrHakVjL/QHaoyV4aDUVVkXQJJJ3NXXM=
+github.com/cenkalti/backoff/v4 v4.1.1 h1:G2HAfAmvm/GcKan2oOQpBXOd2tT2G57ZnZGWa1PxPBQ=
 github.com/cenkalti/backoff/v4 v4.1.1/go.mod h1:scbssz8iZGpm3xbr14ovlUdkxfGXNInqkPWOWmG2CLw=
-github.com/cenkalti/backoff/v4 v4.1.3 h1:cFAlzYUlVYDysBEH2T5hyJZMh3+5+WCBvSnK6Q8UtC4=
-github.com/cenkalti/backoff/v4 v4.1.3/go.mod h1:scbssz8iZGpm3xbr14ovlUdkxfGXNInqkPWOWmG2CLw=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
 github.com/cespare/cp v0.1.0/go.mod h1:SOGHArjBr4JWaSDEVpWpo/hNg6RoKrls6Oh40hiwW+s=
 github.com/cespare/xxhash v1.1.0 h1:a6HrQnmkObjyL+Gs60czilIUGqrzKutQD6XZog3p+ko=

modules/apps/29-fee/transfer_test.go

@@ -30,7 +30,7 @@ func (suite *FeeTestSuite) TestFeeTransfer() {
 
 	msgs := []sdk.Msg{
 		types.NewMsgPayPacketFee(fee, path.EndpointA.ChannelConfig.PortID, path.EndpointA.ChannelID, suite.chainA.SenderAccount.GetAddress().String(), nil),
-		transfertypes.NewMsgTransfer(path.EndpointA.ChannelConfig.PortID, path.EndpointA.ChannelID, coin, suite.chainA.SenderAccount.GetAddress().String(), suite.chainB.SenderAccount.GetAddress().String(), clienttypes.NewHeight(1, 100), 0, nil),
+		transfertypes.NewMsgTransfer(path.EndpointA.ChannelConfig.PortID, path.EndpointA.ChannelID, coin, suite.chainA.SenderAccount.GetAddress().String(), suite.chainB.SenderAccount.GetAddress().String(), clienttypes.NewHeight(1, 100), 0, ""),
 	}
 	res, err := suite.chainA.SendMsgs(msgs...)
 	suite.Require().NoError(err) // message committed

modules/apps/transfer/client/cli/tx.go

@@ -22,7 +22,7 @@ const (
 	flagPacketTimeoutHeight    = "packet-timeout-height"
 	flagPacketTimeoutTimestamp = "packet-timeout-timestamp"
 	flagAbsoluteTimeouts       = "absolute-timeouts"
-	flagMetadata               = "metadata"
+	flagMemo                   = "memo"
 )
 
 // NewTransferTxCmd returns the command to create a NewMsgTransfer transaction
@@ -77,7 +77,7 @@ corresponding to the counterparty channel. Any timeout set to 0 is disabled.`),
 				return err
 			}
 
-			metadataStr, err := cmd.Flags().GetString(flagMetadata)
+			memo, err := cmd.Flags().GetString(flagMemo)
 			if err != nil {
 				return err
 			}
@@ -117,7 +117,7 @@ corresponding to the counterparty channel. Any timeout set to 0 is disabled.`),
 			}
 
 			msg := types.NewMsgTransfer(
-				srcPort, srcChannel, coin, sender, receiver, timeoutHeight, timeoutTimestamp, []byte(metadataStr),
+				srcPort, srcChannel, coin, sender, receiver, timeoutHeight, timeoutTimestamp, memo,
 			)
 			return tx.GenerateOrBroadcastTxCLI(clientCtx, cmd.Flags(), msg)
 		},
@@ -126,7 +126,7 @@ corresponding to the counterparty channel. Any timeout set to 0 is disabled.`),
 	cmd.Flags().String(flagPacketTimeoutHeight, types.DefaultRelativePacketTimeoutHeight, "Packet timeout block height. The timeout is disabled when set to 0-0.")
 	cmd.Flags().Uint64(flagPacketTimeoutTimestamp, types.DefaultRelativePacketTimeoutTimestamp, "Packet timeout timestamp in nanoseconds from now. Default is 10 minutes. The timeout is disabled when set to 0.")
 	cmd.Flags().Bool(flagAbsoluteTimeouts, false, "Timeout flags are used as absolute timeouts.")
-	cmd.Flags().String(flagMetadata, "", "Metadata to be sent along with the packet. The CLI accepts only strings here but you can construct a packet with arbitrary bytes via code.")
+	cmd.Flags().String(flagMemo, "", "Memo to be sent along with the packet.")
 	flags.AddTxFlagsToCmd(cmd)
 
 	return cmd

modules/apps/transfer/ibc_module.go

@@ -1,7 +1,6 @@
 package transfer
 
 import (
-	"encoding/hex"
 	"fmt"
 	"math"
 	"strings"
@@ -195,7 +194,7 @@ func (im IBCModule) OnRecvPacket(
 		sdk.NewAttribute(types.AttributeKeyReceiver, data.Receiver),
 		sdk.NewAttribute(types.AttributeKeyDenom, data.Denom),
 		sdk.NewAttribute(types.AttributeKeyAmount, data.Amount),
-		sdk.NewAttribute(types.AttributeKeyMetadata, hex.EncodeToString(data.Metadata)),
+		sdk.NewAttribute(types.AttributeKeyMemo, data.Memo),
 		sdk.NewAttribute(types.AttributeKeyAckSuccess, fmt.Sprintf("%t", ack.Success())),
 	}
 
@@ -242,7 +241,7 @@ func (im IBCModule) OnAcknowledgementPacket(
 			sdk.NewAttribute(types.AttributeKeyReceiver, data.Receiver),
 			sdk.NewAttribute(types.AttributeKeyDenom, data.Denom),
 			sdk.NewAttribute(types.AttributeKeyAmount, data.Amount),
-			sdk.NewAttribute(types.AttributeKeyMetadata, hex.EncodeToString(data.Metadata)),
+			sdk.NewAttribute(types.AttributeKeyMemo, data.Memo),
 			sdk.NewAttribute(types.AttributeKeyAck, ack.String()),
 		),
 	)
@@ -289,7 +288,7 @@ func (im IBCModule) OnTimeoutPacket(
 			sdk.NewAttribute(types.AttributeKeyRefundReceiver, data.Sender),
 			sdk.NewAttribute(types.AttributeKeyRefundDenom, data.Denom),
 			sdk.NewAttribute(types.AttributeKeyRefundAmount, data.Amount),
-			sdk.NewAttribute(types.AttributeKeyMetadata, hex.EncodeToString(data.Metadata)),
+			sdk.NewAttribute(types.AttributeKeyMemo, data.Memo),
 		),
 	)
 

modules/apps/transfer/keeper/mbt_relay_test.go

@@ -147,7 +147,7 @@ func FungibleTokenPacketFromTla(packet TlaFungibleTokenPacket) FungibleTokenPack
 			packet.Data.Amount,
 			AddressFromString(packet.Data.Sender),
 			AddressFromString(packet.Data.Receiver),
-			nil),
+			""),
 	}
 }
 
@@ -346,7 +346,7 @@ func (suite *KeeperTestSuite) TestModelBasedRelay() {
 							sender.String(),
 							tc.packet.Data.Receiver,
 							suite.chainA.GetTimeoutHeight(), 0, // only use timeout height
-							nil,
+							"",
 						)
 
 						_, err = suite.chainB.GetSimApp().TransferKeeper.Transfer(sdk.WrapSDKContext(suite.chainB.GetContext()), msg)

modules/apps/transfer/keeper/msg_server.go

@@ -30,7 +30,7 @@ func (k Keeper) Transfer(goCtx context.Context, msg *types.MsgTransfer) (*types.
 
 	sequence, err := k.sendTransfer(
 		ctx, msg.SourcePort, msg.SourceChannel, msg.Token, sender, msg.Receiver, msg.TimeoutHeight, msg.TimeoutTimestamp,
-		msg.Metadata)
+		msg.Memo)
 	if err != nil {
 		return nil, err
 	}

modules/apps/transfer/keeper/msg_server_test.go

@@ -66,7 +66,7 @@ func (suite *KeeperTestSuite) TestMsgTransfer() {
 				path.EndpointA.ChannelID,
 				coin, suite.chainA.SenderAccount.GetAddress().String(), suite.chainB.SenderAccount.GetAddress().String(),
 				suite.chainB.GetTimeoutHeight(), 0, // only use timeout height
-				[]byte("custom metadata"),
+				"memo",
 			)
 
 			tc.malleate()

modules/apps/transfer/keeper/relay.go

@@ -57,7 +57,7 @@ func (k Keeper) sendTransfer(
 	receiver string,
 	timeoutHeight clienttypes.Height,
 	timeoutTimestamp uint64,
-	metadata []byte,
+	memo string,
 ) (uint64, error) {
 	channel, found := k.channelKeeper.GetChannel(ctx, sourcePort, sourceChannel)
 	if !found {
@@ -130,7 +130,7 @@ func (k Keeper) sendTransfer(
 	}
 
 	packetData := types.NewFungibleTokenPacketData(
-		fullDenomPath, token.Amount.String(), sender.String(), receiver, metadata,
+		fullDenomPath, token.Amount.String(), sender.String(), receiver, memo,
 	)
 
 	sequence, err := k.ics4Wrapper.SendPacket(ctx, channelCap, sourcePort, sourceChannel, timeoutHeight, timeoutTimestamp, packetData.GetBytes())

modules/apps/transfer/keeper/relay_test.go

@@ -21,7 +21,7 @@ func (suite *KeeperTestSuite) TestSendTransfer() {
 		path          *ibctesting.Path
 		sender        sdk.AccAddress
 		timeoutHeight clienttypes.Height
-		metadata      []byte
+		memo          string
 	)
 
 	testCases := []struct {
@@ -34,9 +34,9 @@ func (suite *KeeperTestSuite) TestSendTransfer() {
 			func() {}, true,
 		},
 		{
-			"successful transfer from source chain with metadata",
+			"successful transfer from source chain with memo",
 			func() {
-				metadata = []byte("metadata")
+				memo = "memo"
 			}, true,
 		},
 		{
@@ -48,11 +48,11 @@ func (suite *KeeperTestSuite) TestSendTransfer() {
 			}, true,
 		},
 		{
-			"successful transfer with IBC token and metadata",
+			"successful transfer with IBC token and memo",
 			func() {
 				// send IBC token back to chainB
 				coin = types.GetTransferCoin(path.EndpointA.ChannelConfig.PortID, path.EndpointA.ChannelID, coin.Denom, coin.Amount)
-				metadata = []byte("metadata")
+				memo = "memo"
 			}, true,
 		},
 		{
@@ -112,11 +112,11 @@ func (suite *KeeperTestSuite) TestSendTransfer() {
 
 			coin = sdk.NewCoin(sdk.DefaultBondDenom, sdk.NewInt(100))
 			sender = suite.chainA.SenderAccount.GetAddress()
-			metadata = []byte{}
+			memo = ""
 			timeoutHeight = suite.chainB.GetTimeoutHeight()
 
 			// create IBC token on chainA
-			transferMsg := types.NewMsgTransfer(path.EndpointB.ChannelConfig.PortID, path.EndpointB.ChannelID, coin, suite.chainB.SenderAccount.GetAddress().String(), suite.chainA.SenderAccount.GetAddress().String(), suite.chainA.GetTimeoutHeight(), 0, nil)
+			transferMsg := types.NewMsgTransfer(path.EndpointB.ChannelConfig.PortID, path.EndpointB.ChannelID, coin, suite.chainB.SenderAccount.GetAddress().String(), suite.chainA.SenderAccount.GetAddress().String(), suite.chainA.GetTimeoutHeight(), 0, "")
 			result, err := suite.chainB.SendMsgs(transferMsg)
 			suite.Require().NoError(err) // message committed
 
@@ -133,7 +133,7 @@ func (suite *KeeperTestSuite) TestSendTransfer() {
 				path.EndpointA.ChannelID,
 				coin, sender.String(), suite.chainB.SenderAccount.GetAddress().String(),
 				timeoutHeight, 0, // only use timeout height
-				metadata,
+				memo,
 			)
 
 			res, err := suite.chainA.GetSimApp().TransferKeeper.Transfer(sdk.WrapSDKContext(suite.chainA.GetContext()), msg)
@@ -158,7 +158,7 @@ func (suite *KeeperTestSuite) TestOnRecvPacket() {
 		trace    types.DenomTrace
 		amount   math.Int
 		receiver string
-		metadata []byte
+		memo     string
 	)
 
 	testCases := []struct {
@@ -168,12 +168,12 @@ func (suite *KeeperTestSuite) TestOnRecvPacket() {
 		expPass      bool
 	}{
 		{"success receive on source chain", func() {}, true, true},
-		{"success receive on source chain with metadata", func() {
-			metadata = []byte("metadata")
+		{"success receive on source chain with memo", func() {
+			memo = "memo"
 		}, true, true},
 		{"success receive with coin from another chain as source", func() {}, false, true},
-		{"success receive with coin from another chain as source with metadata", func() {
-			metadata = []byte("metadata")
+		{"success receive with coin from another chain as source with memo", func() {
+			memo = "memo"
 		}, false, true},
 		{"empty coin", func() {
 			trace = types.DenomTrace{}
@@ -215,14 +215,14 @@ func (suite *KeeperTestSuite) TestOnRecvPacket() {
 			suite.coordinator.Setup(path)
 			receiver = suite.chainB.SenderAccount.GetAddress().String() // must be explicitly changed in malleate
 
-			metadata = []byte{}      // can be explicitly changed in malleate
+			memo = ""                // can be explicitly changed in malleate
 			amount = sdk.NewInt(100) // must be explicitly changed in malleate
 			seq := uint64(1)
 
 			if tc.recvIsSource {
 				// send coin from chainB to chainA, receive them, acknowledge them, and send back to chainB
 				coinFromBToA := sdk.NewCoin(sdk.DefaultBondDenom, sdk.NewInt(100))
-				transferMsg := types.NewMsgTransfer(path.EndpointB.ChannelConfig.PortID, path.EndpointB.ChannelID, coinFromBToA, suite.chainB.SenderAccount.GetAddress().String(), suite.chainA.SenderAccount.GetAddress().String(), clienttypes.NewHeight(1, 110), 0, metadata)
+				transferMsg := types.NewMsgTransfer(path.EndpointB.ChannelConfig.PortID, path.EndpointB.ChannelID, coinFromBToA, suite.chainB.SenderAccount.GetAddress().String(), suite.chainA.SenderAccount.GetAddress().String(), clienttypes.NewHeight(1, 110), 0, memo)
 				res, err := suite.chainB.SendMsgs(transferMsg)
 				suite.Require().NoError(err) // message committed
 
@@ -241,13 +241,13 @@ func (suite *KeeperTestSuite) TestOnRecvPacket() {
 			}
 
 			// send coin from chainA to chainB
-			transferMsg := types.NewMsgTransfer(path.EndpointA.ChannelConfig.PortID, path.EndpointA.ChannelID, sdk.NewCoin(trace.IBCDenom(), amount), suite.chainA.SenderAccount.GetAddress().String(), receiver, clienttypes.NewHeight(1, 110), 0, metadata)
+			transferMsg := types.NewMsgTransfer(path.EndpointA.ChannelConfig.PortID, path.EndpointA.ChannelID, sdk.NewCoin(trace.IBCDenom(), amount), suite.chainA.SenderAccount.GetAddress().String(), receiver, clienttypes.NewHeight(1, 110), 0, memo)
 			_, err := suite.chainA.SendMsgs(transferMsg)
 			suite.Require().NoError(err) // message committed
 
 			tc.malleate()
 
-			data := types.NewFungibleTokenPacketData(trace.GetFullDenomPath(), amount.String(), suite.chainA.SenderAccount.GetAddress().String(), receiver, metadata)
+			data := types.NewFungibleTokenPacketData(trace.GetFullDenomPath(), amount.String(), suite.chainA.SenderAccount.GetAddress().String(), receiver, memo)
 			packet := channeltypes.NewPacket(data.GetBytes(), seq, path.EndpointA.ChannelConfig.PortID, path.EndpointA.ChannelID, path.EndpointB.ChannelConfig.PortID, path.EndpointB.ChannelID, clienttypes.NewHeight(1, 100), 0)
 
 			err = suite.chainB.GetSimApp().TransferKeeper.OnRecvPacket(suite.chainB.GetContext(), packet, data)
@@ -320,7 +320,7 @@ func (suite *KeeperTestSuite) TestOnAcknowledgementPacket() {
 
 			tc.malleate()
 
-			data := types.NewFungibleTokenPacketData(trace.GetFullDenomPath(), amount.String(), suite.chainA.SenderAccount.GetAddress().String(), suite.chainB.SenderAccount.GetAddress().String(), nil)
+			data := types.NewFungibleTokenPacketData(trace.GetFullDenomPath(), amount.String(), suite.chainA.SenderAccount.GetAddress().String(), suite.chainB.SenderAccount.GetAddress().String(), "")
 			packet := channeltypes.NewPacket(data.GetBytes(), 1, path.EndpointA.ChannelConfig.PortID, path.EndpointA.ChannelID, path.EndpointB.ChannelConfig.PortID, path.EndpointB.ChannelID, clienttypes.NewHeight(1, 100), 0)
 
 			preCoin := suite.chainA.GetSimApp().BankKeeper.GetBalance(suite.chainA.GetContext(), suite.chainA.SenderAccount.GetAddress(), trace.IBCDenom())
@@ -416,7 +416,7 @@ func (suite *KeeperTestSuite) TestOnTimeoutPacket() {
 
 			tc.malleate()
 
-			data := types.NewFungibleTokenPacketData(trace.GetFullDenomPath(), amount.String(), sender, suite.chainB.SenderAccount.GetAddress().String(), nil)
+			data := types.NewFungibleTokenPacketData(trace.GetFullDenomPath(), amount.String(), sender, suite.chainB.SenderAccount.GetAddress().String(), "")
 			packet := channeltypes.NewPacket(data.GetBytes(), 1, path.EndpointA.ChannelConfig.PortID, path.EndpointA.ChannelID, path.EndpointB.ChannelConfig.PortID, path.EndpointB.ChannelID, clienttypes.NewHeight(1, 100), 0)
 
 			preCoin := suite.chainA.GetSimApp().BankKeeper.GetBalance(suite.chainA.GetContext(), suite.chainA.SenderAccount.GetAddress(), trace.IBCDenom())

modules/apps/transfer/transfer_test.go

@@ -54,7 +54,7 @@ func (suite *TransferTestSuite) TestHandleMsgTransfer() {
 	coinToSendToB := sdk.NewCoin(sdk.DefaultBondDenom, amount)
 
 	// send from chainA to chainB
-	msg := types.NewMsgTransfer(path.EndpointA.ChannelConfig.PortID, path.EndpointA.ChannelID, coinToSendToB, suite.chainA.SenderAccount.GetAddress().String(), suite.chainB.SenderAccount.GetAddress().String(), timeoutHeight, 0, nil)
+	msg := types.NewMsgTransfer(path.EndpointA.ChannelConfig.PortID, path.EndpointA.ChannelID, coinToSendToB, suite.chainA.SenderAccount.GetAddress().String(), suite.chainB.SenderAccount.GetAddress().String(), timeoutHeight, 0, "")
 	res, err := suite.chainA.SendMsgs(msg)
 	suite.Require().NoError(err) // message committed
 
@@ -80,7 +80,7 @@ func (suite *TransferTestSuite) TestHandleMsgTransfer() {
 	suite.coordinator.Setup(pathBtoC)
 
 	// send from chainB to chainC
-	msg = types.NewMsgTransfer(pathBtoC.EndpointA.ChannelConfig.PortID, pathBtoC.EndpointA.ChannelID, coinSentFromAToB, suite.chainB.SenderAccount.GetAddress().String(), suite.chainC.SenderAccount.GetAddress().String(), timeoutHeight, 0, nil)
+	msg = types.NewMsgTransfer(pathBtoC.EndpointA.ChannelConfig.PortID, pathBtoC.EndpointA.ChannelID, coinSentFromAToB, suite.chainB.SenderAccount.GetAddress().String(), suite.chainC.SenderAccount.GetAddress().String(), timeoutHeight, 0, "")
 	res, err = suite.chainB.SendMsgs(msg)
 	suite.Require().NoError(err) // message committed
 
@@ -104,7 +104,7 @@ func (suite *TransferTestSuite) TestHandleMsgTransfer() {
 	suite.Require().Zero(balance.Amount.Int64())
 
 	// send from chainC back to chainB
-	msg = types.NewMsgTransfer(pathBtoC.EndpointB.ChannelConfig.PortID, pathBtoC.EndpointB.ChannelID, coinSentFromBToC, suite.chainC.SenderAccount.GetAddress().String(), suite.chainB.SenderAccount.GetAddress().String(), timeoutHeight, 0, nil)
+	msg = types.NewMsgTransfer(pathBtoC.EndpointB.ChannelConfig.PortID, pathBtoC.EndpointB.ChannelID, coinSentFromBToC, suite.chainC.SenderAccount.GetAddress().String(), suite.chainB.SenderAccount.GetAddress().String(), timeoutHeight, 0, "")
 	res, err = suite.chainC.SendMsgs(msg)
 	suite.Require().NoError(err) // message committed
 

modules/apps/transfer/types/events.go

@@ -18,5 +18,5 @@ const (
 	AttributeKeyAck            = "acknowledgement"
 	AttributeKeyAckError       = "error"
 	AttributeKeyTraceHash      = "trace_hash"
-	AttributeKeyMetadata       = "metadata"
+	AttributeKeyMemo           = "memo"
 )

modules/apps/transfer/types/msgs.go

@@ -17,7 +17,7 @@ func NewMsgTransfer(
 	sourcePort, sourceChannel string,
 	token sdk.Coin, sender, receiver string,
 	timeoutHeight clienttypes.Height, timeoutTimestamp uint64,
-	metadata []byte,
+	memo string,
 ) *MsgTransfer {
 	return &MsgTransfer{
 		SourcePort:       sourcePort,
@@ -27,7 +27,7 @@ func NewMsgTransfer(
 		Receiver:         receiver,
 		TimeoutHeight:    timeoutHeight,
 		TimeoutTimestamp: timeoutTimestamp,
-		Metadata:         metadata,
+		Memo:             memo,
 	}
 }