Revert vendor directory to support old golang (GOPATH mode)

gomodule is still in progress to migrate for now, hence multus
team decide to keep vendor directory to support build without
gomodule.

vendor/github.com/imdario/mergo/map.go

@@ -0,0 +1,146 @@
+// Copyright 2014 Dario Castañé. All rights reserved.
+// Copyright 2009 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.
+
+// Based on src/pkg/reflect/deepequal.go from official
+// golang's stdlib.
+
+package mergo
+
+import (
+	"fmt"
+	"reflect"
+	"unicode"
+	"unicode/utf8"
+)
+
+func changeInitialCase(s string, mapper func(rune) rune) string {
+	if s == "" {
+		return s
+	}
+	r, n := utf8.DecodeRuneInString(s)
+	return string(mapper(r)) + s[n:]
+}
+
+func isExported(field reflect.StructField) bool {
+	r, _ := utf8.DecodeRuneInString(field.Name)
+	return r >= 'A' && r <= 'Z'
+}
+
+// Traverses recursively both values, assigning src's fields values to dst.
+// The map argument tracks comparisons that have already been seen, which allows
+// short circuiting on recursive types.
+func deepMap(dst, src reflect.Value, visited map[uintptr]*visit, depth int) (err error) {
+	if dst.CanAddr() {
+		addr := dst.UnsafeAddr()
+		h := 17 * addr
+		seen := visited[h]
+		typ := dst.Type()
+		for p := seen; p != nil; p = p.next {
+			if p.ptr == addr && p.typ == typ {
+				return nil
+			}
+		}
+		// Remember, remember...
+		visited[h] = &visit{addr, typ, seen}
+	}
+	zeroValue := reflect.Value{}
+	switch dst.Kind() {
+	case reflect.Map:
+		dstMap := dst.Interface().(map[string]interface{})
+		for i, n := 0, src.NumField(); i < n; i++ {
+			srcType := src.Type()
+			field := srcType.Field(i)
+			if !isExported(field) {
+				continue
+			}
+			fieldName := field.Name
+			fieldName = changeInitialCase(fieldName, unicode.ToLower)
+			if v, ok := dstMap[fieldName]; !ok || isEmptyValue(reflect.ValueOf(v)) {
+				dstMap[fieldName] = src.Field(i).Interface()
+			}
+		}
+	case reflect.Struct:
+		srcMap := src.Interface().(map[string]interface{})
+		for key := range srcMap {
+			srcValue := srcMap[key]
+			fieldName := changeInitialCase(key, unicode.ToUpper)
+			dstElement := dst.FieldByName(fieldName)
+			if dstElement == zeroValue {
+				// We discard it because the field doesn't exist.
+				continue
+			}
+			srcElement := reflect.ValueOf(srcValue)
+			dstKind := dstElement.Kind()
+			srcKind := srcElement.Kind()
+			if srcKind == reflect.Ptr && dstKind != reflect.Ptr {
+				srcElement = srcElement.Elem()
+				srcKind = reflect.TypeOf(srcElement.Interface()).Kind()
+			} else if dstKind == reflect.Ptr {
+				// Can this work? I guess it can't.
+				if srcKind != reflect.Ptr && srcElement.CanAddr() {
+					srcPtr := srcElement.Addr()
+					srcElement = reflect.ValueOf(srcPtr)
+					srcKind = reflect.Ptr
+				}
+			}
+			if !srcElement.IsValid() {
+				continue
+			}
+			if srcKind == dstKind {
+				if err = deepMerge(dstElement, srcElement, visited, depth+1); err != nil {
+					return
+				}
+			} else {
+				if srcKind == reflect.Map {
+					if err = deepMap(dstElement, srcElement, visited, depth+1); err != nil {
+						return
+					}
+				} else {
+					return fmt.Errorf("type mismatch on %s field: found %v, expected %v", fieldName, srcKind, dstKind)
+				}
+			}
+		}
+	}
+	return
+}
+
+// Map sets fields' values in dst from src.
+// src can be a map with string keys or a struct. dst must be the opposite:
+// if src is a map, dst must be a valid pointer to struct. If src is a struct,
+// dst must be map[string]interface{}.
+// It won't merge unexported (private) fields and will do recursively
+// any exported field.
+// If dst is a map, keys will be src fields' names in lower camel case.
+// Missing key in src that doesn't match a field in dst will be skipped. This
+// doesn't apply if dst is a map.
+// This is separated method from Merge because it is cleaner and it keeps sane
+// semantics: merging equal types, mapping different (restricted) types.
+func Map(dst, src interface{}) error {
+	var (
+		vDst, vSrc reflect.Value
+		err        error
+	)
+	if vDst, vSrc, err = resolveValues(dst, src); err != nil {
+		return err
+	}
+	// To be friction-less, we redirect equal-type arguments
+	// to deepMerge. Only because arguments can be anything.
+	if vSrc.Kind() == vDst.Kind() {
+		return deepMerge(vDst, vSrc, make(map[uintptr]*visit), 0)
+	}
+	switch vSrc.Kind() {
+	case reflect.Struct:
+		if vDst.Kind() != reflect.Map {
+			return ErrExpectedMapAsDestination
+		}
+	case reflect.Map:
+		if vDst.Kind() != reflect.Struct {
+			return ErrExpectedStructAsDestination
+		}
+	default:
+		return ErrNotSupported
+	}
+	return deepMap(vDst, vSrc, make(map[uintptr]*visit), 0)
+}