Fix panic on JSON marshal if PITRestoreDateTime is not a pointer (#1368)

Co-authored-by: Viacheslav Sarzhan <[email protected]>

Author: pcman312

pkg/apis/pgv2.percona.com/v2/perconapgbackup_types.go

@@ -129,7 +129,7 @@ func (t *PITRestoreDateTime) UnmarshalJSON(b []byte) (err error) {
 	return nil
 }
 
-func (t *PITRestoreDateTime) MarshalJSON() ([]byte, error) {
+func (t PITRestoreDateTime) MarshalJSON() ([]byte, error) {
 	if t.Time == nil {
 		return []byte("null"), nil
 	}

pkg/apis/pgv2.percona.com/v2/perconapgbackup_types_test.go

@@ -0,0 +1,69 @@
+package v2
+
+import (
+	"encoding/json"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+func TestPITRestoreDateTime_MarshalJSON(t *testing.T) {
+	type testCase struct {
+		data     any
+		expected string
+	}
+	tests := map[string]testCase{
+		"default": {
+			data:     PITRestoreDateTime{},
+			expected: `null`,
+		},
+		"pointer": {
+			data:     &PITRestoreDateTime{},
+			expected: `null`,
+		},
+		"nil pointer": {
+			data:     (*PITRestoreDateTime)(nil),
+			expected: `null`,
+		},
+		"non-pointer zero date time": {
+			data: PITRestoreDateTime{
+				Time: ptr(metav1.NewTime(time.Time{})),
+			},
+			expected: `"0001-01-01 00:00:00.000000+0000"`,
+		},
+		"pointer zero date time": {
+			data: &PITRestoreDateTime{
+				Time: ptr(metav1.NewTime(time.Time{})),
+			},
+			expected: `"0001-01-01 00:00:00.000000+0000"`,
+		},
+		"non-pointer with date time": {
+			data: PITRestoreDateTime{
+				Time: ptr(metav1.NewTime(time.Date(2025, time.November, 21, 13, 14, 15, 345600000, time.UTC))),
+			},
+			expected: `"2025-11-21 13:14:15.345600+0000"`,
+		},
+		"pointer with date time": {
+			data: &PITRestoreDateTime{
+				Time: ptr(metav1.NewTime(time.Date(2025, time.November, 21, 13, 14, 15, 345600000, time.UTC))),
+			},
+			expected: `"2025-11-21 13:14:15.345600+0000"`,
+		},
+	}
+
+	for name, test := range tests {
+		t.Run(name, func(t *testing.T) {
+			require.NotPanics(t, func() {
+				b, err := json.Marshal(test.data)
+				require.NoError(t, err)
+				require.JSONEq(t, test.expected, string(b))
+			})
+		})
+	}
+}
+
+func ptr[T any](v T) *T {
+	return &v
+}