question: public void register ( UUID transactionId , RepositoryConnection conn ) throws RepositoryException { synchronized ( primaryCache ) { if ( primaryCache . getIfPresent ( transactionId ) == null ) { final CacheEntry cacheEntry = new CacheEntry ( conn ) ; primaryCache . put ( transactionId , cacheEntry ) ; secondaryCache . put ( transactionId , cacheEntry ) ; logger . debug ( "registered transaction {} " , transactionId ) ; } else { logger . error ( "transaction already registered: {}" , transactionId ) ; throw new RepositoryException ( "transaction with id " + transactionId . toString ( ) + " already registered." ) ; } } }
target:  Register a new transaction with the given id and connection.