public FileSegment(FileSegment previous, long end)
{
Index = previous.Index;
Start = previous.Start;
End = end;
Type = previous.Type;
Key = previous.Key;
}
public FileSegment(int index, long start, long end, FileSegmentType type)
{
Index = index;
Start = start;
End = end;
Type = type;
Key = new FileSegmentKey(index, type);
}