question: public static BlockMirror checkIfBlockMirrorExistsInDB ( String mirrorNativeGuid , DbClient dbClient ) { List < BlockMirror > activeMirrors = CustomQueryUtility . getActiveBlockMirrorByNativeGuid ( dbClient , mirrorNativeGuid ) ; Iterator < BlockMirror > mirrorItr = activeMirrors . iterator ( ) ; return mirrorItr . hasNext ( ) ? mirrorItr . next ( ) : null ; }
target:  Check if the given native GUID String exists in the database for a BlockMirror object.