code: public ShardingTransactionManager getTransactionManager(final TransactionType transactionType) {
          ShardingTransactionManager result = transactionManagerMap.get(transactionType);
          if (TransactionType.LOCAL != transactionType) {
              Preconditions.checkNotNull(result, "Cannot find transaction manager of [%s]", transactionType);
          }
          return result;
      }
docs: Get sharding transaction manager.
  
  @param transactionType transaction type
  @return sharding transaction manager