SystemPoweredByBlock.php

<?php

namespace Drupal\system\Plugin\Block;

use Drupal\Core\Block\BlockBase;

/**
 * Provides a 'Powered by Drupal' block.
 *
 * @Block(
 *   id = "system_powered_by_block",
 *   admin_label = @Translation("Powered by Drupal")
 * )
 */
class SystemPoweredByBlock extends BlockBase {
    
    /**
     * {@inheritdoc}
     */
    public function defaultConfiguration() {
        return [
            'label_display' => FALSE,
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function build() {
        return [
            '#markup' => '<span>' . $this->t('Powered by <a href=":poweredby">Drupal</a>', [
                ':poweredby' => 'https://www.drupal.org',
            ]) . '</span>',
        ];
    }

}