wp-admin/includes/class-wp-list-table.php:1251Gets the name of the primary column.
string public function get_primary_column() { return $this->get_primary_column_name(); }Introduced in 4.4.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-admin/includes/class-wp-list-table.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.