creates the table with both columns being defined as NOT NULL:
The request is a warning when defining a multi-column table constraint primary key if any of the columns comprising said PK are not defined already to be NOT NULL.
Personally, green field at least, I find that to be reasonable. Especially if we are altering catalog metadata to define the columns to be not null, as opposed to say the case when a check constraint has a "col is not null" condition that could never pass even though the column itself is null-able.