question: public AggRecord ( ) { this . aggregatedRecordBuilder = AggregatedRecord . newBuilder ( ) ; this . aggregatedMessageSizeBytes = 0 ; this . explicitHashKeys = new KeySet ( ) ; this . partitionKeys = new KeySet ( ) ; this . aggExplicitHashKey = "" ; this . aggPartitionKey = "" ; try { this . md5 = MessageDigest . getInstance ( MESSAGE_DIGEST_NAME ) ; } catch ( NoSuchAlgorithmException e ) { throw new IllegalStateException ( "Could not create an MD5 message digest." , e ) ; } }
target:  Construct a new (empty) aggregated Kinesis record.