diff --git a/vendor/go.etcd.io/etcd/raft/raftpb/confstate.go b/vendor/go.etcd.io/etcd/raft/raftpb/confstate.go
new file mode 100644
index 0000000..4bda932
--- /dev/null
+++ b/vendor/go.etcd.io/etcd/raft/raftpb/confstate.go
@@ -0,0 +1,45 @@
+// Copyright 2019 The etcd Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package raftpb
+
+import (
+	"fmt"
+	"reflect"
+	"sort"
+)
+
+// Equivalent returns a nil error if the inputs describe the same configuration.
+// On mismatch, returns a descriptive error showing the differences.
+func (cs ConfState) Equivalent(cs2 ConfState) error {
+	cs1 := cs
+	orig1, orig2 := cs1, cs2
+	s := func(sl *[]uint64) {
+		*sl = append([]uint64(nil), *sl...)
+		sort.Slice(*sl, func(i, j int) bool { return (*sl)[i] < (*sl)[j] })
+	}
+
+	for _, cs := range []*ConfState{&cs1, &cs2} {
+		s(&cs.Voters)
+		s(&cs.Learners)
+		s(&cs.VotersOutgoing)
+		s(&cs.LearnersNext)
+		cs.XXX_unrecognized = nil
+	}
+
+	if !reflect.DeepEqual(cs1, cs2) {
+		return fmt.Errorf("ConfStates not equivalent after sorting:\n%+#v\n%+#v\nInputs were:\n%+#v\n%+#v", cs1, cs2, orig1, orig2)
+	}
+	return nil
+}