Cannot detect the default value for a generated always as identity column

[fluca1978]

When a column is defined as generated always as identity, the COLUMN_DEF returned by the column_info method is empty. This apparently is correct, since pg_get_expr() does not return anything.
However, this could be a problem with other tools, like DBIx::Schema::Loader that are not able to detect that the column is "attached" to a sequence behind the scenes.