Why does writer not use HDFS hflush when close file?

We use ORC for writing to HDFS. Today we found some corrupted files without PostScript.

Code that writes files is looked as:

writer.close()
moveFile()

So it is guaranted file was closed without error. The only idea I have is that footer had not been flushed before file was moved. Is it possible because writer does not call HDFS hflush()?