chore: move gov migrations to right folder

UPGRADING.md

@@ -160,7 +160,7 @@ This allows you to remove the replace directive `replace github.com/gogo/protobu
 
 Please use the `ghcr.io/cosmos/proto-builder` image (version >= `0.11.5`) for generating protobuf files.
 
-See which buf commit for `cosmos/cosmos-sdk` to pin in your `buf.yaml` file [here](./proto/README.md)
+See which buf commit for `cosmos/cosmos-sdk` to pin in your `buf.yaml` file [here](./proto/README.md).
 
 #### `{accepts,implements}_interface` proto annotations
 
@@ -231,9 +231,7 @@ modified to set the new parameter to the desired value.
 
 ##### New Proposal.Proposer field
 
-The `Proposal` proto has been updated with proposer field. For proposal state migraton developers can call `v4.AddProposerAddressToProposal` in their upgrade handler to update all existing proposal and make them compatible and this migration is optional.
-
-> This migration is optional, if chain wants to cancel previous proposals which are active (deposit or voting period) they can do this proposals state migration.
+The `Proposal` proto has been updated with proposer field. For proposal state migraton developers can call `v4.AddProposerAddressToProposal` in their upgrade handler to update all existing proposal and make them compatible and **this migration is optional**.
 
 ```go
 import (

x/gov/migrations/v4/store.go

@@ -1,13 +1,17 @@
 package v4
 
 import (
+	"fmt"
+	"sort"
+
 	"cosmossdk.io/store/prefix"
 	storetypes "cosmossdk.io/store/types"
 
 	"github.com/cosmos/cosmos-sdk/codec"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/x/gov/exported"
 	v1 "github.com/cosmos/cosmos-sdk/x/gov/migrations/v1"
+	"github.com/cosmos/cosmos-sdk/x/gov/types"
 	govv1 "github.com/cosmos/cosmos-sdk/x/gov/types/v1"
 )
 
@@ -78,3 +82,50 @@ func MigrateStore(ctx sdk.Context, storeKey storetypes.StoreKey, legacySubspace
 
 	return migrateParams(ctx, storeKey, legacySubspace, cdc)
 }
+
+// AddProposerAddressToProposal will add proposer to proposal and set to the store. This function is optional.
+func AddProposerAddressToProposal(ctx sdk.Context, storeKey storetypes.StoreKey, cdc codec.BinaryCodec, proposals map[uint64]string) error {
+	proposalIDs := make([]uint64, 0, len(proposals))
+
+	for proposalID := range proposals {
+		proposalIDs = append(proposalIDs, proposalID)
+	}
+
+	// sort the proposalIDs
+	sort.Slice(proposalIDs, func(i, j int) bool { return proposalIDs[i] < proposalIDs[j] })
+
+	store := ctx.KVStore(storeKey)
+
+	for _, proposalID := range proposalIDs {
+		if len(proposals[proposalID]) == 0 {
+			return fmt.Errorf("found missing proposer for proposal ID: %d", proposalID)
+		}
+
+		if _, err := sdk.AccAddressFromBech32(proposals[proposalID]); err != nil {
+			return fmt.Errorf("invalid proposer address : %s", proposals[proposalID])
+		}
+
+		bz := store.Get(types.ProposalKey(proposalID))
+		var proposal govv1.Proposal
+		if err := cdc.Unmarshal(bz, &proposal); err != nil {
+			panic(err)
+		}
+
+		// Check if proposal is active
+		if proposal.Status != govv1.ProposalStatus_PROPOSAL_STATUS_VOTING_PERIOD &&
+			proposal.Status != govv1.ProposalStatus_PROPOSAL_STATUS_DEPOSIT_PERIOD {
+			return fmt.Errorf("invalid proposal : %s, proposal not active", proposals[proposalID])
+		}
+
+		proposal.Proposer = proposals[proposalID]
+
+		// set the new proposal with proposer
+		bz, err := cdc.Marshal(&proposal)
+		if err != nil {
+			panic(err)
+		}
+		store.Set(types.ProposalKey(proposal.Id), bz)
+	}
+
+	return nil
+}