jurt: print an array with java.util.Arrays.toString

Change-Id: I76431b67f9f6fdde2906d6d8082457ef0847108e
Reviewed-on: https://gerrit.libreoffice.org/11964
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>