Converts this instant to the number of milliseconds from the epoch
of 1970-01-01T00:00:00Z.
!(p)
If this instant represents a point on the time-line too far _in the future
or past to fit _in a {@code long} milliseconds, then an exception is thrown.
!(p)
If this instant has greater than millisecond precision, then the conversion
will drop any excess precision information as though the amount _in nanoseconds
was subject to integer division by one million.
@return the number of milliseconds since the epoch of 1970-01-01T00:00:00Z
@throws ArithmeticException if numeric overflow occurs
Converts this instant to the number of milliseconds from the epoch of 1970-01-01T00:00:00Z. !(p) If this instant represents a point on the time-line too far _in the future or past to fit _in a {@code long} milliseconds, then an exception is thrown. !(p) If this instant has greater than millisecond precision, then the conversion will drop any excess precision information as though the amount _in nanoseconds was subject to integer division by one million.
@return the number of milliseconds since the epoch of 1970-01-01T00:00:00Z @throws ArithmeticException if numeric overflow occurs