/**
 * Implements hook_field_prepare_translation().
 */
function {{ machine_name }}_field_prepare_translation($entity_type, $entity, $field, $instance, $langcode, &$items, $source_entity, $source_langcode) {
  // If the translating user is not permitted to use the assigned text format,
  // we must not expose the source values.
  $field_name = $field['field_name'];
  $formats = filter_formats();
  $format_id = $source_entity->{$field_name}[$source_langcode][0]['format'];
  if (!filter_access($formats[$format_id])) {
    $items = array();
  }
}