FSDirectory createOutput re-creates file because it opens stream with
TRUNCATE_EXISTING. What is the way to open existing file and append data? I
used it at Lucene 4.1 to create store with raw messages. I could use
Files.newOutputStream directly to do that but I just want to understand
what is the idea of the design that prohibits appending to existing data? I
can't keep IndexOutput always open, at least after restart of application I
have to re-open existing data and continue to append. What is the way
Lucene suggest for that now?
