vendor: update buildkit to master@31c870e82a48

Signed-off-by: Justin Chadwell <me@jedevc.com>

vendor/github.com/aws/smithy-go/encoding/json/object.go

@@ -0,0 +1,40 @@
+package json
+
+import (
+	"bytes"
+)
+
+// Object represents the encoding of a JSON Object type
+type Object struct {
+	w          *bytes.Buffer
+	writeComma bool
+	scratch    *[]byte
+}
+
+func newObject(w *bytes.Buffer, scratch *[]byte) *Object {
+	w.WriteRune(leftBrace)
+	return &Object{w: w, scratch: scratch}
+}
+
+func (o *Object) writeKey(key string) {
+	escapeStringBytes(o.w, []byte(key))
+	o.w.WriteRune(colon)
+}
+
+// Key adds the given named key to the JSON object.
+// Returns a Value encoder that should be used to encode
+// a JSON value type.
+func (o *Object) Key(name string) Value {
+	if o.writeComma {
+		o.w.WriteRune(comma)
+	} else {
+		o.writeComma = true
+	}
+	o.writeKey(name)
+	return newValue(o.w, o.scratch)
+}
+
+// Close encodes the end of the JSON Object
+func (o *Object) Close() {
+	o.w.WriteRune(rightBrace)
+}