/**
* Returns a copy of this time with the specified amount added.
* <p>
* This returns an {@code OffsetTime}, based on this one, with the amount
* in terms of the unit added. If it is not possible to add the amount, because the
* unit is not supported or for some other reason, an exception is thrown.
* <p>
* If the field is a {@link ChronoUnit} then the addition is implemented by
* {@link LocalTime#plus(long, TemporalUnit)}.
* The offset is not part of the calculation and will be unchanged in the result.
* <p>
* If the field is not a {@code ChronoUnit}, then the result of this method
* is obtained by invoking {@code TemporalUnit.addTo(Temporal, long)}
* passing {@code this} as the argument. In this case, the unit determines
* whether and how to perform the addition.
* <p>
* This instance is immutable and unaffected by this method call.
*
* @param int $amountToAdd the amount of the unit to add to the result, may be negative
* @param TemporalUnit $unit the unit of the amount to add, not null
* @return OffsetTime an {@code OffsetTime} based on this time with the specified amount added, not null
* @throws DateTimeException if the addition cannot be made
* @throws UnsupportedTemporalTypeException if the unit is not supported
* @throws ArithmeticException if numeric overflow occurs
*/
public function plus($amountToAdd, TemporalUnit $unit)
{
if ($unit instanceof ChronoUnit) {
return $this->_with($this->time->plus($amountToAdd, $unit), $this->offset);
}
return $unit->addTo($this, $amountToAdd);
}