protected function mergeOptions(array $options)
 {
     $options = parent::mergeOptions($options);
     $options['entry_type'] = CurrencyType::class;
     $options['select2'] = array_merge_recursive(isset($options['select2']) ? $options['select2'] : array(), array('enabled' => true));
     return $options;
 }
 protected function mergeOptions(array $options)
 {
     $options = parent::mergeOptions($options);
     $options['class'] = $this::SINGLE_INT_ID_CLASS;
     return $options;
 }