abci: add changelog entry for mempool_error field (#6770)

Follow up from PR: #6740

CHANGELOG_PENDING.md

@@ -30,6 +30,7 @@ Friendly reminder: We have a [bug bounty program](https://hackerone.com/tendermi
   - [ABCI] \#5447 Remove `SetOption` method from `ABCI.Client` interface
   - [ABCI] \#5447 Reset `Oneof` indexes for  `Request` and `Response`.
   - [ABCI] \#5818 Use protoio for msg length delimitation. Migrates from int64 to uint64 length delimiters.
+  - [ABCI] \#3546 Add `mempool_error` field to `ResponseCheckTx`. This field will contain an error string if Tendermint encountered an error while adding a transaction to the mempool. (@williambanfield)
   - [Version] \#6494 `TMCoreSemVer` has been renamed to `TMVersion`.
     - It is not required any longer to set ldflags to set version strings
   - [abci/counter] \#6684 Delete counter example app

abci/types/types.pb.go

@@ -1827,17 +1827,19 @@ func (m *ResponseBeginBlock) GetEvents() []Event {
 }
 
 type ResponseCheckTx struct {
-	Code         uint32  `protobuf:"varint,1,opt,name=code,proto3" json:"code,omitempty"`
-	Data         []byte  `protobuf:"bytes,2,opt,name=data,proto3" json:"data,omitempty"`
-	Log          string  `protobuf:"bytes,3,opt,name=log,proto3" json:"log,omitempty"`
-	Info         string  `protobuf:"bytes,4,opt,name=info,proto3" json:"info,omitempty"`
-	GasWanted    int64   `protobuf:"varint,5,opt,name=gas_wanted,proto3" json:"gas_wanted,omitempty"`
-	GasUsed      int64   `protobuf:"varint,6,opt,name=gas_used,proto3" json:"gas_used,omitempty"`
-	Events       []Event `protobuf:"bytes,7,rep,name=events,proto3" json:"events,omitempty"`
-	Codespace    string  `protobuf:"bytes,8,opt,name=codespace,proto3" json:"codespace,omitempty"`
-	Sender       string  `protobuf:"bytes,9,opt,name=sender,proto3" json:"sender,omitempty"`
-	Priority     int64   `protobuf:"varint,10,opt,name=priority,proto3" json:"priority,omitempty"`
-	MempoolError string  `protobuf:"bytes,11,opt,name=mempool_error,json=mempoolError,proto3" json:"mempool_error,omitempty"`
+	Code      uint32  `protobuf:"varint,1,opt,name=code,proto3" json:"code,omitempty"`
+	Data      []byte  `protobuf:"bytes,2,opt,name=data,proto3" json:"data,omitempty"`
+	Log       string  `protobuf:"bytes,3,opt,name=log,proto3" json:"log,omitempty"`
+	Info      string  `protobuf:"bytes,4,opt,name=info,proto3" json:"info,omitempty"`
+	GasWanted int64   `protobuf:"varint,5,opt,name=gas_wanted,proto3" json:"gas_wanted,omitempty"`
+	GasUsed   int64   `protobuf:"varint,6,opt,name=gas_used,proto3" json:"gas_used,omitempty"`
+	Events    []Event `protobuf:"bytes,7,rep,name=events,proto3" json:"events,omitempty"`
+	Codespace string  `protobuf:"bytes,8,opt,name=codespace,proto3" json:"codespace,omitempty"`
+	Sender    string  `protobuf:"bytes,9,opt,name=sender,proto3" json:"sender,omitempty"`
+	Priority  int64   `protobuf:"varint,10,opt,name=priority,proto3" json:"priority,omitempty"`
+	// mempool_error is set by Tendermint.
+	// ABCI applictions creating a ResponseCheckTX should not set mempool_error.
+	MempoolError string `protobuf:"bytes,11,opt,name=mempool_error,json=mempoolError,proto3" json:"mempool_error,omitempty"`
 }
 
 func (m *ResponseCheckTx) Reset()         { *m = ResponseCheckTx{} }

proto/tendermint/abci/types.proto

@@ -186,17 +186,20 @@ message ResponseBeginBlock {
 }
 
 message ResponseCheckTx {
-  uint32         code          = 1;
-  bytes          data          = 2;
-  string         log           = 3;  // nondeterministic
-  string         info          = 4;  // nondeterministic
-  int64          gas_wanted    = 5 [json_name = "gas_wanted"];
-  int64          gas_used      = 6 [json_name = "gas_used"];
-  repeated Event events        = 7 [(gogoproto.nullable) = false, (gogoproto.jsontag) = "events,omitempty"];
-  string         codespace     = 8;
-  string         sender        = 9;
-  int64          priority      = 10;
-  string         mempool_error = 11;
+  uint32         code       = 1;
+  bytes          data       = 2;
+  string         log        = 3;  // nondeterministic
+  string         info       = 4;  // nondeterministic
+  int64          gas_wanted = 5 [json_name = "gas_wanted"];
+  int64          gas_used   = 6 [json_name = "gas_used"];
+  repeated Event events     = 7 [(gogoproto.nullable) = false, (gogoproto.jsontag) = "events,omitempty"];
+  string         codespace  = 8;
+  string         sender     = 9;
+  int64          priority   = 10;
+
+  // mempool_error is set by Tendermint.
+  // ABCI applictions creating a ResponseCheckTX should not set mempool_error.
+  string mempool_error = 11;
 }
 
 message ResponseDeliverTx {