func (imageState *ImageState) MarshalJSON() ([]byte, error) {
	imageState.lock.Lock()
	defer imageState.lock.Unlock()

	return json.Marshal(&struct {
		Image         *Image
		PulledAt      time.Time
		LastUsedAt    time.Time
		PullSucceeded bool
	}{
		Image:         imageState.Image,
		PulledAt:      imageState.PulledAt,
		LastUsedAt:    imageState.LastUsedAt,
		PullSucceeded: imageState.PullSucceeded,
	})
}
func (imageState *ImageState) MarshalJSON() ([]byte, error) {
	imageState.lock.Lock()
	defer imageState.lock.Unlock()

	return json.Marshal(&struct {
		Image         *Image
		PulledAt      time.Time
		LastUsedAt    time.Time
		PullSucceeded bool
	}{
		Image:         imageState.Image,
		PulledAt:      imageState.PulledAt,
		LastUsedAt:    imageState.LastUsedAt,
		PullSucceeded: imageState.PullSucceeded,
	})
}
// MarshalJSON marshals image state