question: protected String hash ( String key ) { try { MessageDigest gen = HASH_GENERATOR . get ( ) ; byte [ ] keyBytes = key . getBytes ( "UTF-8" ) ; gen . update ( keyBytes , 0 , keyBytes . length ) ; byte [ ] binaryhash = gen . digest ( ) ; return ENCODER . encodeToString ( binaryhash ) ; } catch ( Exception e ) { LOG . warn ( "Failed to get hash encoding for key: {}" , key , e ) ; } return null ; }
target:  Get the hash encoding of a key string.