What designed pattern is applied when implementing the methods of Temperal

In Java8's date and time package java.time, the interface Temporal is implemented by LocalDate, LocalTime, and LocalDateTime etc. Especially the the LocalDate and LocalTime implemented the plus(TemporalAmount amountToAdd) smartly, say LocalDate and LocalTime use the parameter's method - amountToAdd.addTo to implement the plus method

This seems to make use of some design patterns. Could anyone tell which design pattern is used in the mentioned implementation?