code: public OutputStream writeFile(@NotNull final Transaction txn, final long fileDescriptor) {
          return new VfsOutputStream(this, txn, fileDescriptor, null);
      }
docs: Returns {@linkplain OutputStream} to write the contents of the specified file from the beginning. Writing to
  the returned stream doesn't change the {@linkplain File}'s last modified time.
  
  @param txn            {@linkplain Transaction} instance
  @param fileDescriptor file descriptor
  @return {@linkplain OutputStream} to write the contents of the specified file from the beginning
  @see #readFile(Transaction, File)
  @see #readFile(Transaction, long)
  @see #readFile(Transaction, File, long)
  @see #writeFile(Transaction, File)
  @see #writeFile(Transaction, File, long)
  @see #writeFile(Transaction, long, long)
  @see #appendFile(Transaction, File)
  @see #touchFile(Transaction, File)
  @see File#getDescriptor()
  @see File#getLastModified()