/**
  * {@inheritdoc}
  */
 public function getFilterLabels()
 {
     $info = parent::getFilterLabels();
     $info['placeholder'] = $this->t('Enter block, theme or category');
     $info['description'] = $this->t('Enter a part of the block, theme or category to filter by.');
     return $info;
 }
 /**
  * {@inheritdoc}
  */
 public function buildHeader()
 {
     $header['label'] = $this->t('Field');
     if ($this->displayBundle()) {
         $header['bundle'] = $this->baseEntityInfo->getBundleLabel() ?: $this->t('Bundle');
     }
     return $header + parent::buildHeader();
 }