DCP-7055 scanner (brscan4) fix
The printer has always worked in Ubuntu out of the box.
The old driver page at the Brother website contains drivers that won't work on Bionic no longer though. You need to use a newer version provided here: http://support.brother.com/g/b/downloadlist.aspx?c=us&lang=en&prod=mfcj470dw_us_eu_as&os=128
The old page has the 0.4.2 version of the driver, but Bionic needs 0.4.5 dated May 2018 on that page above. Best to use the installer script at the top of that page (it will add a second printer you can delete, but fixes the scanner).