Add go.mod; build on buster with recent go

vendor/github.com/golang/protobuf/proto/wire.go

+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package proto
+
+import (
+	protoV2 "google.golang.org/protobuf/proto"
+	"google.golang.org/protobuf/runtime/protoiface"
+)
+
+// Size returns the size in bytes of the wire-format encoding of m.
+func Size(m Message) int {
+	if m == nil {
+		return 0
+	}
+	mi := MessageV2(m)
+	return protoV2.Size(mi)
+}
+
+// Marshal returns the wire-format encoding of m.
+func Marshal(m Message) ([]byte, error) {
+	b, err := marshalAppend(nil, m, false)
+	if b == nil {
+		b = zeroBytes
+	}
+	return b, err
+}
+
+var zeroBytes = make([]byte, 0, 0)
+
+func marshalAppend(buf []byte, m Message, deterministic bool) ([]byte, error) {
+	if m == nil {
+		return nil, ErrNil
+	}
+	mi := MessageV2(m)
+	nbuf, err := protoV2.MarshalOptions{
+		Deterministic: deterministic,
+		AllowPartial:  true,
+	}.MarshalAppend(buf, mi)
+	if err != nil {
+		return buf, err
+	}
+	if len(buf) == len(nbuf) {
+		if !mi.ProtoReflect().IsValid() {
+			return buf, ErrNil
+		}
+	}
+	return nbuf, checkRequiredNotSet(mi)
+}
+
+// Unmarshal parses a wire-format message in b and places the decoded results in m.
+//
+// Unmarshal resets m before starting to unmarshal, so any existing data in m is always
+// removed. Use UnmarshalMerge to preserve and append to existing data.
+func Unmarshal(b []byte, m Message) error {
+	m.Reset()
+	return UnmarshalMerge(b, m)
+}
+
+// UnmarshalMerge parses a wire-format message in b and places the decoded results in m.
+func UnmarshalMerge(b []byte, m Message) error {
+	mi := MessageV2(m)
+	out, err := protoV2.UnmarshalOptions{
+		AllowPartial: true,
+		Merge:        true,
+	}.UnmarshalState(protoiface.UnmarshalInput{
+		Buf:     b,
+		Message: mi.ProtoReflect(),
+	})
+	if err != nil {
+		return err
+	}
+	if out.Flags&protoiface.UnmarshalInitialized > 0 {
+		return nil
+	}
+	return checkRequiredNotSet(mi)
+}

vendor/github.com/golang/protobuf/proto/wrappers.go

+// Copyright 2019 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package proto
+
+// Bool stores v in a new bool value and returns a pointer to it.
+func Bool(v bool) *bool { return &v }
+
+// Int stores v in a new int32 value and returns a pointer to it.
+//
+// Deprecated: Use Int32 instead.
+func Int(v int) *int32 { return Int32(int32(v)) }
+
+// Int32 stores v in a new int32 value and returns a pointer to it.
+func Int32(v int32) *int32 { return &v }
+
+// Int64 stores v in a new int64 value and returns a pointer to it.
+func Int64(v int64) *int64 { return &v }
+
+// Uint32 stores v in a new uint32 value and returns a pointer to it.
+func Uint32(v uint32) *uint32 { return &v }
+
+// Uint64 stores v in a new uint64 value and returns a pointer to it.
+func Uint64(v uint64) *uint64 { return &v }
+
+// Float32 stores v in a new float32 value and returns a pointer to it.
+func Float32(v float32) *float32 { return &v }
+
+// Float64 stores v in a new float64 value and returns a pointer to it.
+func Float64(v float64) *float64 { return &v }
+
+// String stores v in a new string value and returns a pointer to it.
+func String(v string) *string { return &v }

vendor/github.com/golang/protobuf/ptypes/doc.go

+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package ptypes provides functionality for interacting with well-known types.
+package ptypes