NavWalker Bootstrap Error (won’t dropdown)

Wrong container_id and menu_class. See WP Bootstrap NavWalker Usage section.

<?php
wp_nav_menu( array(
    'theme_location'    => 'primary',
    'depth'             => 2,
    'container'         => 'div',
    'container_class'   => 'collapse navbar-collapse',
    'container_id'      => 'bs-example-navbar-collapse-1',
    'menu_class'        => 'nav navbar-nav',
    'fallback_cb'       => 'WP_Bootstrap_Navwalker::fallback',
    'walker'            => new WP_Bootstrap_Navwalker(),
) );