code: public <I, O> List<O> groupExecute(final Collection<ShardingExecuteGroup<I>> inputGroups, final ShardingGroupExecuteCallback<I, O> callback) throws SQLException {
          return groupExecute(inputGroups, null, callback, false);
      }
docs: Execute for group.
  
  @param inputGroups input groups
  @param callback sharding execute callback
  @param <I> type of input value
  @param <O> type of return value
  @return execute result
  @throws SQLException throw if execute failure