Cmb2: Support multilevel arrays within multicheck field type

[DevinWalker]

Expected Behavior:

When you create a new field with option values such as:

array(
                'name'    => 'Test Multi Checkbox',
                'desc'    => 'field description (optional)',
                'id'      => 'wiki_test_multicheckbox',
                'type'    => 'multicheck',
                'options' => array(
                    'check1' => 'Check One',
                    'check2' => 'Check Two',
                    'check3' => 'Check Three',
                    array(
                        'check1' => 'Check One',
                        'check2' => 'Check Two',
                        'check3' => 'Check Three',
                    )
                ),
            ),

You should see a multi-check option that's hierarchical as such:

as such:

Actual Behavior:

You get the following PHP error:

( ! ) Notice: Array to string conversion in /app/public/wp-content/plugins/give/includes/libraries/cmb2/includes/types/CMB2_Type_Multi_Base.php on line 42

Steps to reproduce (I have confirmed I can reproduce this issue on the trunk branch):

1. Create a multicheck field type as above
2. Turn on WP_Debug
   

   CMB2 Field Registration Code:

add_action( 'cmb2_admin_init', 'yourprefix_register_demo_metabox' );
function yourprefix_register_demo_metabox() {

    $cmb = new_cmb2_box( array(
        // Box Config...
    ) );

    $cmb->add_field( array(
        array(
                'name'    => 'Test Multi Checkbox',
                'desc'    => 'field description (optional)',
                'id'      => 'wiki_test_multicheckbox',
                'type'    => 'multicheck',
                'options' => array(
                    'check1' => 'Check One',
                    'check2' => 'Check Two',
                    'check3' => 'Check Three',
                    array(
                        'check1' => 'Check One',
                        'check2' => 'Check Two',
                        'check3' => 'Check Three',
                    )
                ),
            ),
    ) );
}

[tw2113]

I trust you enough to assume right away that this is, for sure, a legit bug that could use addressing.

[DevinWalker]

Thanks for the trust 👍

If I get the time I'll submit a PR with the fix to address it 🎉

[phh]

I there an update here or any new features to use instead?

[tw2113]

Haven't seen anything for new movement for this issue specifically. New features available to everyone can be read about in the changelogs found at https://github.com/CMB2/CMB2/releases