Add Fee granter field

x/auth/ante/fee_grant.go

@@ -5,9 +5,9 @@ import (
 	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
 )
 
-// RejectFeeGranterDecorator is a placeholder AnteDecorator for fee grants for
-// when that functionality is enabled. Currently it simpy rejects transactions
-// which have the Fee.granter field set.
+// RejectFeeGranterDecorator is an AnteDecorator which rejects transactions which
+// have the Fee.granter field set. It is to be used by chains which do not support
+// fee grants.
 type RejectFeeGranterDecorator struct{}
 
 // NewRejectFeeGranterDecorator returns a new RejectFeeGranterDecorator.

x/auth/legacy/legacytx/stdtx_test.go

@@ -67,6 +67,9 @@ func TestStdTx(t *testing.T) {
 
 	feePayer := tx.GetSigners()[0]
 	require.Equal(t, addr, feePayer)
+
+	feeGranter := tx.FeeGranter()
+	require.Empty(t, feeGranter)
 }
 
 func TestStdSignBytes(t *testing.T) {

x/auth/tx/builder_test.go

@@ -289,3 +289,25 @@ func TestBuilderFeePayer(t *testing.T) {
 		})
 	}
 }