/**
  * Integrity check
  *
  * @return bool
  */
 protected function integrity()
 {
     $result = true;
     $this->progress->start(1);
     $result &= array_keys($this->source->getStructure(self::SOURCE)->getFields()) == $this->structure[MapInterface::TYPE_SOURCE][self::SOURCE];
     $result &= array_keys($this->destination->getStructure(self::DESTINATION)->getFields()) == $this->structure[MapInterface::TYPE_DEST][self::DESTINATION];
     $this->progress->advance();
     $this->progress->finish();
     return (bool) $result;
 }