NULL input for array_agg()?

Hi,

During reviewing aggregates ORDER BY, I was reading spec and found
description like:

== snip ==

Of the rows in the aggregation, the following do not qualify:
— If DISTINCT is specified, then redundant duplicates.
— Every row in which the <value expression> evaluates to the null value.

== /snip ==

... and array_agg() is among the functions that description above
refers to. So I wonder if array_agg doesn't accept NULL input (with
STRICT trans function). Did we discussed about this issue when
implementing it for 8.4?

Regards,

--
Hitoshi Harada