LlamaButton.php

<?php

namespace Drupal\ckeditor_test\Plugin\CKEditorPlugin;

use Drupal\ckeditor\CKEditorPluginButtonsInterface;

/**
 * Defines a "LlamaButton" plugin, with a toolbar builder-enabled "llama" feature.
 *
 * @CKEditorPlugin(
 *   id = "llama_button",
 *   label = @Translation("Llama Button")
 * )
 */
class LlamaButton extends Llama implements CKEditorPluginButtonsInterface {
    
    /**
     * {@inheritdoc}
     */
    public function getButtons() {
        return [
            'Llama' => [
                'label' => $this->t('Insert Llama'),
            ],
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function getFile() {
        return $this->moduleList
            ->getPath('ckeditor_test') . '/js/llama_button.js';
    }

}