Adds a specified number of years to the DateTimeOffset object.
An object whose value is the sum of the date and time represented by the current DateTimeOffset object and the number of years represented by years.
Unlike most of the other methods that add a single time interval unit (such as minutes or days) to a date and time value, DateTimeOffset.AddYears(int) does not enable you to add fractional parts of a year. To add a time that consists of other time units in addition to years to a DateTimeOffset object, use the DateTimeOffset.Add(TimeSpan) method.
This method returns a new DateTimeOffset object. It does not modify the value of the current object by adding months to its date and time.