Need to set java scaling for 5k monitor (hdmi)

I've just installed jjazzlab-3.2.1 on a debian system with a 5k monitor.  The fonts, etc. are displaying at a very small size - nearly unreadable and definitely unusable.  This is a well known problem with java - by default it assumes the 'standard' pre-5k resolution and cannot detect the monitor resolution (at least not under linux). 

The solution is to set the VM property sun.java2d.uiScale, e.g

java -J-Dsun.java2d.uiScale=2 -jar some_swing_application.jar
Presumably I need to modify the launch script JJazzLab-3.2.1-Linux/bin/jjazzlab to set this property when the jjazzlab java app is launched.  I've tried, but I haven't gotten it right.

I tried the following change.  At the bottom of the jjazzlab sh script, there's a case section that appears to launch the java app:

case "`uname`" in
   Darwin*)
       eval exec sh '"$nbexec"' \
           --jdkhome '"$jdkhome"' \
           -J-Xdock:name='"$APP_DOCK_NAME"' \
           '"-J-Xdock:icon=$progdir/../../$APPNAME.icns"' \
           --clusters '"$clusters"' \
           --userdir '"${userdir}"' \
           --cachedir '"${cachedir}"' \
           ${default_options} \
           "$args"
       ;;
   *)  
      sh=sh
      # #73162: Ubuntu uses the ancient Bourne shell, which does not implement trap well.
      if [ -x /bin/bash ]
      then
          sh=/bin/bash
      fi
      eval exec $sh '"$nbexec"' \
           --jdkhome '"$jdkhome"' \          
           --clusters '"$clusters"' \
           --userdir '"${userdir}"' \
           --cachedir '"${cachedir}"' \
           ${default_options} \
           "$args"
      exit 1
       ;;
esac
Presumably the 'Darwin' case is for OS X, so I added the property setting -J-Dsun.java2d.uiScale=2 to the second eval: