Disable recognition of Binary(Unm|M)arshaler in CBOR serializer.

The underlying CBOR library will by default encode a value to and from byte string if its type
implements encoding.BinaryMarshaler or encoding.BinaryUnmarshaler, respectively. This is now
disabled via an option to avoid diverging from JSON in those cases.

staging/src/k8s.io/apimachinery/pkg/runtime/serializer/cbor/internal/modes/decode.go

@@ -135,6 +135,10 @@ var Decode cbor.DecMode = func() cbor.DecMode {
 
 		// Reject anything other than the simple values true, false, and null.
 		SimpleValues: simpleValues,
+
+		// Disable default recognition of types implementing encoding.BinaryUnmarshaler,
+		// which is not recognized for JSON decoding.
+		BinaryUnmarshaler: cbor.BinaryUnmarshalerNone,
 	}.DecMode()
 	if err != nil {
 		panic(err)

staging/src/k8s.io/apimachinery/pkg/runtime/serializer/cbor/internal/modes/decode_test.go

@@ -29,6 +29,12 @@ import (
 	"github.com/google/go-cmp/cmp"
 )
 
+type int64BinaryUnmarshaler int64
+
+func (i *int64BinaryUnmarshaler) UnmarshalBinary(_ []byte) error {
+	return nil
+}
+
 func TestDecode(t *testing.T) {
 	hex := func(h string) []byte {
 		b, err := hex.DecodeString(h)
@@ -203,6 +209,20 @@ func TestDecode(t *testing.T) {
 			want:          "AQIDBA==",
 			assertOnError: assertNilError,
 		},
+		{
+			name: "into non-string type implementing BinaryUnmarshaler",
+			in:   hex("40"), // ''
+			into: int64BinaryUnmarshaler(7),
+			assertOnError: assertOnConcreteError(func(t *testing.T, e *cbor.UnmarshalTypeError) {
+				want := &cbor.UnmarshalTypeError{
+					CBORType: "byte string",
+					GoType:   reflect.TypeFor[int64BinaryUnmarshaler]().String(),
+				}
+				if e.CBORType != want.CBORType || e.GoType != want.GoType {
+					t.Errorf("expected %q, got %q", want, e)
+				}
+			}),
+		},
 	})
 
 	group(t, "text string", []test{

staging/src/k8s.io/apimachinery/pkg/runtime/serializer/cbor/internal/modes/encode.go

@@ -87,6 +87,10 @@ var Encode cbor.EncMode = func() cbor.EncMode {
 		// base64 encoding of the original bytes. No base64 encoding or decoding needs to be
 		// performed for []byte-to-CBOR-to-[]byte roundtrips.
 		ByteSliceLaterFormat: cbor.ByteSliceLaterFormatBase64,
+
+		// Disable default recognition of types implementing encoding.BinaryMarshaler, which
+		// is not recognized for JSON encoding.
+		BinaryMarshaler: cbor.BinaryMarshalerNone,
 	}.EncMode()
 	if err != nil {
 		panic(err)

staging/src/k8s.io/apimachinery/pkg/runtime/serializer/cbor/internal/modes/encode_test.go

@@ -26,6 +26,12 @@ import (
 	"github.com/google/go-cmp/cmp"
 )
 
+type int64BinaryMarshaler int64
+
+func (i int64BinaryMarshaler) MarshalBinary() ([]byte, error) {
+	return []byte{}, nil
+}
+
 func TestEncode(t *testing.T) {
 	for _, tc := range []struct {
 		name          string
@@ -34,6 +40,12 @@ func TestEncode(t *testing.T) {
 		want          []byte
 		assertOnError func(t *testing.T, e error)
 	}{
+		{
+			name:          "implementations of BinaryMarshaler are ignored",
+			in:            int64BinaryMarshaler(7),
+			want:          []byte{0x07},
+			assertOnError: assertNilError,
+		},
 		{
 			name: "all duplicate fields are ignored", // Matches behavior of JSON serializer.
 			in: struct {