piping for flushometer???

Hi

my house was bulit in 1935, i originally had 2 flushometers, 1 on 1st floor and 1 on 2nd floor.

they both were fed from the same 1 inch riser that went up the wet wall

the 2nd floor was removed and made it a normal toilet and the 1st floor remains

i had the riser replaced and in the basmt were the 1 inch riser went up the wet wall there was a 1 inch pipe that ran up with it for 4 feet or so then was capped off

my plumber just assumed they were gonna use it for something else but didnt so they capped it off


my question is was this piece of pipe in there for a purpose? maybe a chamber of some sort?

thanx

Possibly someone's misguided attempt at an air chamber to minimize water hammer.