refactor!: change GetSigners return type to []sdk.AccAddress (#9915)

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## Description
Changes the `sdk.Msg` interface method `GetSigners() []string` to `GetSigners() []sdk.AccAddress`

Closes: #9885 


+change GetSigner return type
+defer address checking to each msg's `ValidateBasic`  method
+clean up consistency/redundancy issues in validate basic


---

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- [ ] updated the relevant documentation or specification
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### Reviewers Checklist

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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 
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- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

types/tx/types.go

@@ -97,14 +97,9 @@ func (t *Tx) GetSigners() []sdk.AccAddress {
 
 	for _, msg := range t.GetMsgs() {
 		for _, addr := range msg.GetSigners() {
-			if !seen[addr] {
-				signer, err := sdk.AccAddressFromBech32(addr)
-				if err != nil {
-					panic(err)
-				}
-
-				signers = append(signers, signer)
-				seen[addr] = true
+			if !seen[addr.String()] {
+				signers = append(signers, addr)
+				seen[addr.String()] = true
 			}
 		}
 	}
@@ -195,22 +190,3 @@ func RegisterInterfaces(registry codectypes.InterfaceRegistry) {
 	registry.RegisterInterface("cosmos.tx.v1beta1.Tx", (*sdk.Tx)(nil))
 	registry.RegisterImplementations((*sdk.Tx)(nil), &Tx{})
 }
-
-// ValidateMsg calls the `sdk.Msg.ValidateBasic()`
-// also validates all the signers are valid bech32 addresses.
-func ValidateMsg(msg sdk.Msg) error {
-	err := msg.ValidateBasic()
-	if err != nil {
-		return err
-	}
-
-	signers := msg.GetSigners()
-	for _, signer := range signers {
-		_, err = sdk.AccAddressFromBech32(signer)
-		if err != nil {
-			return err
-		}
-	}
-
-	return nil
-}

types/tx/types_test.go

@@ -1,43 +0,0 @@
-package tx_test
-
-import (
-	"testing"
-
-	"github.com/cosmos/cosmos-sdk/testutil/testdata"
-	"github.com/cosmos/cosmos-sdk/types/tx"
-	"github.com/stretchr/testify/suite"
-)
-
-type testMsgSuite struct {
-	suite.Suite
-}
-
-func TestValidateMsg(t *testing.T) {
-	suite.Run(t, new(testMsgSuite))
-}
-
-func (s *testMsgSuite) TestMsg() {
-	cases := []struct {
-		signer []byte
-		expErr bool
-	}{
-		{
-			[]byte(""),
-			true,
-		},
-		{
-			[]byte("validAddress"),
-			false,
-		},
-	}
-
-	for _, c := range cases {
-		msg := testdata.NewTestMsg(c.signer)
-		err := tx.ValidateMsg(msg)
-		if c.expErr {
-			s.Require().Error(err)
-		} else {
-			s.Require().NoError(err)
-		}
-	}
-}

types/tx_msg.go

@@ -15,10 +15,10 @@ type (
 		// doesn't require access to any other information.
 		ValidateBasic() error
 
-		// Signers returns the bech32-encoded addrs of signers that must sign.
+		// Signers returns the addrs of signers that must sign.
 		// CONTRACT: All signatures must be present to be valid.
 		// CONTRACT: Returns addrs in some deterministic order.
-		GetSigners() []string
+		GetSigners() []AccAddress
 	}
 
 	// Fee defines an interface for an application application-defined concrete

types/tx_msg_test.go

@@ -23,7 +23,7 @@ func (s *testMsgSuite) TestMsg() {
 
 	msg := testdata.NewTestMsg(accAddr)
 	s.Require().NotNil(msg)
-	s.Require().Equal([]string{accAddr.String()}, msg.GetSigners())
+	s.Require().True(accAddr.Equals(msg.GetSigners()[0]))
 	s.Require().Equal("TestMsg", msg.Route())
 	s.Require().Equal("Test message", msg.Type())
 	s.Require().Nil(msg.ValidateBasic())