Returns a copy of this date-time with the specified period added.
This method returns a new date-time based on this date-time with the specified period added.
This can be used to add any period that is defined by a unit, for example to add years, months or days.
The unit is responsible for the details of the calculation, including the resolution
of any edge cases in the calculation.
The calculation for date and time units differ.
Date units operate on the local time-line.
The period is first added to the local date-time, then converted back
to a zoned date-time using the zone ID.
The conversion uses
#ofLocal(LocalDateTime,ZoneId,ZoneOffset)with the offset before the addition.
Time units operate on the instant time-line.
The period is first added to the local date-time, then converted back to
a zoned date-time using the zone ID.
The conversion uses
#ofInstant(LocalDateTime,ZoneOffset,ZoneId)with the offset before the addition.
This instance is immutable and unaffected by this method call.