Helper function to get the default value for a field on an entity.
\Drupal\Core\Entity\EntityInterface $entity: The entity for the operation.
$field: The field structure.
$instance: The instance structure.
$langcode: The field language to fill-in with the default value.
function field_get_default_value(EntityInterface $entity, $field, $instance, $langcode = NULL) {
$items = array();
if (!empty($instance['default_value_function'])) {
$function = $instance['default_value_function'];
$items = $function($entity, $field, $instance, $langcode);
}
elseif (!empty($instance['default_value'])) {
$items = $instance['default_value'];
}
return $items;
}