A DESCRIPTION OF THE REQUEST :
A comment in
sun/nio/fs/UnixFileAttributes#toFileTime(long,long)
 ( http://grepcode.com/file/repository.grepcode.com/java/root/jdk/openjdk/8-b132/sun/nio/fs/UnixFileAttributes.java#UnixFileAttributes.toFileTime%28long%2Clong%29 ) states:

// truncate to microseconds to avoid overflow with timestamps
// way out into the future. We can re-visit this if FileTime
// is updated to define a from(secs,nsecs) method.

It seems like it's possible to re-visit this decision now, since FileTime provides a "from(Instant)" method since
1.8, which would make it possible to up the resolution to nanoseconds.

I sent a mail to nio-discuss regarding this, and Alan Bateman asked me to report this bug: http://mail.openjdk.java.net/pipermail/nio-discuss/2017-June/000736.html


JUSTIFICATION :
In my case I would like the full resolution of the underlying fs in order to be able to produce equal timestamps to system utilities such as "diff".

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
That FileTime timestamps aren't truncated to nearest microseconds, but have the full nanosecond resolution of the underlying file system.
ACTUAL -
I see truncation to nearest microsecond.

---------- BEGIN SOURCE ----------
public static void main(String[] args) throws IOException, InterruptedException {
        Path file = Files.createTempFile("test", "test");
        String fsTimestamp = "2017-01-01 01:01:01.123456789";
        String[] cmd = {"touch", "-m", "-d", fsTimestamp, file.toString()};
        Process process = Runtime.getRuntime().exec(
                cmd);
        int exitCode = process.waitFor();
        if (exitCode != 0) {
            throw new RuntimeException("Command '" + Arrays.toString(cmd) + "' got exit code " + exitCode);
        }
        FileTime time = Files.getLastModifiedTime(file);
        String javaTimestamp = time.toInstant().atZone(ZoneOffset.UTC).format(DateTimeFormatter.ofPattern("uuuu-MM-dd HH:mm:ss.SSSSSSSSS"));
        if (!javaTimestamp.equals(fsTimestamp)) {
            throw new IllegalStateException("Expected fs timestamp to be '" + fsTimestamp + "', but was '" + javaTimestamp + "'");
        }
    }

// Output:
// Exception in thread "main" java.lang.IllegalStateException: Expected fs timestamp to be '2017-01-01 01:01:01.123456789', but was '2017-01-01 00:01:01.123456000'

---------- END SOURCE ----------