question: public static TXCommitMessage combine ( Set < TXCommitMessage > msgSet ) { assert msgSet != null ; TXCommitMessage firstPart = null ; Iterator < TXCommitMessage > it = msgSet . iterator ( ) ; while ( it . hasNext ( ) ) { if ( firstPart == null ) { firstPart = it . next ( ) ; continue ; } firstPart . combine ( it . next ( ) ) ; } return firstPart ; }
target:  Combines a set of small TXCommitMessages that belong to one transaction into a txCommitMessage that represents an entire transaction. At commit time the txCommitMessage sent to each node can be a subset of the transaction, this method will combine those subsets into a complete message.