QuickTabsBlock.php

<?php

namespace Drupal\quicktabs\Plugin\Derivative;

use Drupal\Component\Plugin\Derivative\DeriverBase;

/**
 * Provides block plugin definitions for quicktabs blocks.
 *
 * @see \Drupal\mymodule\Plugin\Block\QuickTabsBlock
 */
class QuickTabsBlock extends DeriverBase {
    
    /**
     * {@inheritdoc}
     */
    public function getDerivativeDefinitions($base_plugin_definition) {
        foreach (\Drupal::entityTypeManager()->getStorage('quicktabs_instance')
            ->loadMultiple() as $machine_name => $entity) {
            $this->derivatives[$machine_name] = $base_plugin_definition;
            $this->derivatives[$machine_name]['admin_label'] = 'QuickTabs - ' . $entity->label();
        }
        return parent::getDerivativeDefinitions($base_plugin_definition);
    }

}