fix: exporting the blockParams regression (cosmos#13029)

## Description

Closes: cosmos#13024


---

### Author Checklist

*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*

I have...

- [x] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [x] added `!` to the type prefix if API or client breaking change
- [x] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#pr-targeting))
- [x] provided a link to the relevant issue or specification
- [x] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/main/docs/building-modules)
- [x] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#testing)
- [x] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [x] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

CHANGELOG.md

@@ -135,6 +135,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (sdk/dec_coins) [#12903](https://github.com/cosmos/cosmos-sdk/pull/12903) Fix nil `DecCoin` creation when converting `Coins` to `DecCoins`
 * (x/upgrade) [#12906](https://github.com/cosmos/cosmos-sdk/pull/12906) Fix upgrade failure by moving downgrade verification logic after store migration.
 * (store) [#12945](https://github.com/cosmos/cosmos-sdk/pull/12945) Fix nil end semantics in store/cachekv/iterator when iterating a dirty cache.
+* (export) [#13029](https://github.com/cosmos/cosmos-sdk/pull/13029) Fix exporting the blockParams regression.
 
 ### Deprecated
 

server/export.go

@@ -82,8 +82,9 @@ func ExportCmd(appExporter types.AppExporter, defaultNodeHome string) *cobra.Com
 			doc.InitialHeight = exported.Height
 			doc.ConsensusParams = &tmproto.ConsensusParams{
 				Block: tmproto.BlockParams{
-					MaxBytes: exported.ConsensusParams.Block.MaxBytes,
-					MaxGas:   exported.ConsensusParams.Block.MaxGas,
+					MaxBytes:   exported.ConsensusParams.Block.MaxBytes,
+					MaxGas:     exported.ConsensusParams.Block.MaxGas,
+					TimeIotaMs: doc.ConsensusParams.Block.TimeIotaMs,
 				},
 				Evidence: tmproto.EvidenceParams{
 					MaxAgeNumBlocks: exported.ConsensusParams.Evidence.MaxAgeNumBlocks,
@@ -104,6 +105,7 @@ func ExportCmd(appExporter types.AppExporter, defaultNodeHome string) *cobra.Com
 			}
 
 			cmd.SetOut(cmd.OutOrStdout())
+			cmd.SetErr(cmd.OutOrStderr())
 			cmd.Println(string(sdk.MustSortJSON(encoded)))
 			return nil
 		},

tests/e2e/server/export_test.go

@@ -35,7 +35,7 @@ import (
 func TestExportCmd_ConsensusParams(t *testing.T) {
 	tempDir := t.TempDir()
 
-	_, ctx, _, cmd := setupApp(t, tempDir)
+	_, ctx, genDoc, cmd := setupApp(t, tempDir)
 
 	output := &bytes.Buffer{}
 	cmd.SetOut(output)
@@ -50,6 +50,7 @@ func TestExportCmd_ConsensusParams(t *testing.T) {
 
 	require.Equal(t, simtestutil.DefaultConsensusParams.Block.MaxBytes, exportedGenDoc.ConsensusParams.Block.MaxBytes)
 	require.Equal(t, simtestutil.DefaultConsensusParams.Block.MaxGas, exportedGenDoc.ConsensusParams.Block.MaxGas)
+	require.Equal(t, genDoc.ConsensusParams.Block.TimeIotaMs, exportedGenDoc.ConsensusParams.Block.TimeIotaMs)
 
 	require.Equal(t, simtestutil.DefaultConsensusParams.Evidence.MaxAgeDuration, exportedGenDoc.ConsensusParams.Evidence.MaxAgeDuration)
 	require.Equal(t, simtestutil.DefaultConsensusParams.Evidence.MaxAgeNumBlocks, exportedGenDoc.ConsensusParams.Evidence.MaxAgeNumBlocks)