1:1 put through ports in aggregator

What value is put forward in 1:1 put-through ports of aggregators?

It's the value of the last record of the group coming along. E. g:

Input (order matters!)

Group-by-column	Non-group-by-column
1	A
1	B
1	C
2	c
2	a
2	b

Output:

Group-by-column	Non-group-by-column
1	C
2	b