func objectPartIndex(parts []ObjectPartInfo, partNumber int) int {
	for i, part := range parts {
		if partNumber == part.Number {
			return i
		}
	}
	return -1
}

// AddObjectPart - add a new object part in order.
func (fi *FileInfo) AddObjectPart(partNumber int, partETag string, partSize, actualSize int64, modTime time.Time, idx []byte, checksums map[string]string) {
	partInfo := ObjectPartInfo{
		Number:     partNumber,