WP_List_Table::get_bulk_actions()

Description

The format is an associative array where each element represents either a top level option value and label, or an array representing an optgroup and its options.

For a standard option, the array element key is the field value and the array element value is the field label.

For an optgroup, the array element key is the label and the array element value is an associative array of options as above.

Example:

[
    'edit'         => 'Edit',
    'delete'       => 'Delete',
    'Change State' => [
        'feature' => 'Featured',
        'sale'    => 'On Sale',
    ]
]