question: public static String id ( ) { String id = UID . id ( System . currentTimeMillis ( ) , UID . random ( ) ) ; try { while ( Helper . exists ( id , Repo . class ) ) { id = UID . id ( System . currentTimeMillis ( ) , UID . random ( ) ) ; } } catch ( Exception e ) { log . error ( e . getMessage ( ) , e ) ; } return id ; }
target:  get the unique id of repo