Hello Bernard!
Nice question!, *. operator is used to spread all elements in a list...
assert ['cat', 'elephant']*.size() == [3, 8]
while *: is used to spread or combine maps, so you could do something like this:
def argMap = [b:2, c:3, d:4]
fancyMethod(a:1, *:argMap) // You can see this complies the "argument" production in the groovy grammar
You could also see this link
http://marc.info/?l=groovy-user&m=126217908601838
Hope this helps!
Regards,
Serch