javaunohelper: Iterate over each Entry in a Map

Change-Id: I12a3348c297ddddcfd2902c1cbb04bd0ce35b15e
Reviewed-on: https://gerrit.libreoffice.org/10846
Reviewed-by: David Tardon <dtardon@redhat.com>
Tested-by: David Tardon <dtardon@redhat.com>