UMLR — adding error

There seems to be an error in the latest UML 2.5 spec:
16.13.5 Examples
A ReduceAction can be used to reduce a list of numbers to the sum of the numbers. Such a ReduceAction has one InputPin for a collection of numbers, one OutputPin for a number and an addition function as the reducer Behavior. For example, suppose the input collection has four integers: (2, 7, 5, 3). The result of applying the ReduceAction to this collection with an addition function is 11. With the default of isOrdered=false, this can be computed in a number of ways, for example, ( ( (2+7) + 5) + 3), (2 + (7 + (5 + 3))), ((2 + 7) + (5 + 3)).
If I understand the text correctly, the result must be 17.
Please reply to this mail because I use the Beta 2 spec in my courses.
Sicerely yours,
Mit freundlichen Grüßen,
Götz Wankelmuth