protected function addToolbarButtons()
    {
        // Render SAVE type buttons:
        // The action of each button is decided by its name attribute. (See doProcessData())
        $buttonBar = $this->moduleTemplate->getDocHeaderComponent()->getButtonBar();
        $saveSplitButton = $buttonBar->makeSplitButton();

        // SAVE button:
        $saveButton = $buttonBar->makeInputButton()
            ->setTitle(htmlspecialchars($this->languageService->sL('LLL:EXT:lang/Resources/Private/Language/locallang_core.xlf:rm.saveDoc')))
            ->setName('_savedok')
            ->setValue('1')
            ->setForm('EditDocumentController')
            ->setIcon($this->moduleTemplate->getIconFactory()->getIcon(
                'actions-document-save',
                \TYPO3\CMS\Core\Imaging\Icon::SIZE_SMALL
            ));
        $saveSplitButton->addItem($saveButton, true);

        // SAVE & CLOSE button:
        $saveAndCloseButton = $buttonBar->makeInputButton()
            ->setTitle(htmlspecialchars($this->languageService->sL('LLL:EXT:lang/Resources/Private/Language/locallang_core.xlf:rm.saveCloseDoc')))
            ->setName('_saveandclosedok')
            ->setValue('1')
            ->setForm('EditDocumentController')
            ->setClasses('t3js-editform-submitButton')
            ->setIcon($this->moduleTemplate->getIconFactory()->getIcon(
                'actions-document-save-close',
                \TYPO3\CMS\Core\Imaging\Icon::SIZE_SMALL
            ));
        $saveSplitButton->addItem($saveAndCloseButton);

        $buttonBar->addButton($saveSplitButton, \TYPO3\CMS\Backend\Template\Components\ButtonBar::BUTTON_POSITION_LEFT, 2);

        // CLOSE button:
        $closeButton = $buttonBar->makeLinkButton()
            ->setTitle(htmlspecialchars($this->languageService->sL('LLL:EXT:lang/Resources/Private/Language/locallang_core.xlf:rm.closeDoc')))
            ->setHref('#')
            ->setClasses('t3js-editform-close')
            ->setIcon($this->moduleTemplate->getIconFactory()->getIcon(
                'actions-view-go-back',
                \TYPO3\CMS\Core\Imaging\Icon::SIZE_SMALL
            ));
        $buttonBar->addButton($closeButton);
    }