<?php

$value = !empty($field['default_value']) ? $field['default_value'] : '';
?>
<input type="hidden" <?php 
echo wp_kses_post($this->get_render_attribute_string($field_key));
?> value="<?php 
echo esc_attr($value);
?>" placeholder="<?php 
echo esc_attr($field['placeholder']);
?>" />