agent/taskresource/volume/volumestatus.go
func (vs *VolumeStatus) MarshalJSON() ([]byte, error) {
	if vs == nil {
		return nil, nil
	}
	return []byte(`"` + vs.String() + `"`), nil
}
func (vs *VolumeStatus) MarshalJSON() ([]byte, error) {
	if vs == nil {
		return nil, nil
	}
	return []byte(`"` + vs.String() + `"`), nil
}
// MarshalJSON overrides the logic for JSON-encoding the ResourceStatus type