/**
  * Update thumbnail asset
  *
  * @action update
  * @param string $id
  * @param KalturaThumbAsset $thumbAsset
  * @return KalturaThumbAsset
  * @throws KalturaErrors::ENTRY_ID_NOT_FOUND
  * @validateUser asset::entry id edit 
  */
 function updateAction($id, KalturaThumbAsset $thumbAsset)
 {
     $dbThumbAsset = assetPeer::retrieveById($id);
     if (!$dbThumbAsset || !$dbThumbAsset instanceof thumbAsset) {
         throw new KalturaAPIException(KalturaErrors::THUMB_ASSET_ID_NOT_FOUND, $id);
     }
     $dbEntry = $dbThumbAsset->getentry();
     if (!$dbEntry) {
         throw new KalturaAPIException(KalturaErrors::ENTRY_ID_NOT_FOUND, $dbThumbAsset->getEntryId());
     }
     $dbThumbAsset = $thumbAsset->toUpdatableObject($dbThumbAsset);
     $dbThumbAsset->save();
     if ($dbEntry->getCreateThumb() && $dbThumbAsset->hasTag(thumbParams::TAG_DEFAULT_THUMB)) {
         $this->setAsDefaultAction($dbThumbAsset->getId());
     }
     $thumbAsset = new KalturaThumbAsset();
     $thumbAsset->fromObject($dbThumbAsset);
     return $thumbAsset;
 }