Returns the string representation of this FileTime. The string
is returned in the ISO 8601 format:
YYYY-MM-DDThh:mm:ss[.s+]Z
where " [.s+]" represents a dot followed by one of more digits
for the decimal fraction of a second. It is only present when the decimal
fraction of a second is not zero. For example,
FileTime.fromMillis(1234567890000L).toString() yields
"2009-02-13T23:31:30Z", and FileTime.fromMillis(1234567890123L).toString()
yields "2009-02-13T23:31:30.123Z".
A FileTime is primarily intended to represent the value of a
file's time stamp. Where used to represent extreme values, where
the year is less than " 0001" or greater than " 9999" then
this method deviates from ISO 8601 in the same manner as the
XML Schema
language. That is, the year may be expanded to more than four digits
and may be negative-signed. If more than four digits then leading zeros
are not present. The year before " 0001" is " -0001".
Diagram: Attribute