Added java part of the concat benchmark

Signed-off-by: Laszlo Hornyak <laszlo.hornyak@gmail.com>
some customization of the test code

Signed-off-by: Laszlo Hornyak <laszlo.hornyak@gmail.com>
removed license header from pom comment, it was from archetype

Signed-off-by: Laszlo Hornyak <laszlo.hornyak@gmail.com>