/**
  * @param DataValue $dataValue
  */
 private function processDataValue(DataValue $dataValue)
 {
     if ($dataValue instanceof EntityIdValue) {
         $entityId = $dataValue->getEntityId();
         $this->entityIds[$entityId->getSerialization()] = $entityId;
     } elseif ($dataValue instanceof QuantityValue) {
         $unitUri = $dataValue->getUnit();
         $this->processUri($unitUri);
     }
     // TODO: EntityIds from GlobeCoordinateValue's globe URI (Wikidata, not local item URI!)
     // TODO: EntityIds from TimeValue's calendar URI (Wikidata, not local item URI!)
 }