Depending on the circumstances, sometimes there will be records write into a cache writer and a cache reader(Pipe 6) will read out the records and combine with another dataset(Pipe 5) to produce a final report. Other time, no record will be write into the cache writer. As a result, no record will be read out via the cache reader(Pipe 6). Therefore, the final output will just consists of records of the other dataset(Pipe 5). How do I get the protocol to run even when there are no records in the no_restriction cache(Pipe 6)?