java: final fields that can be static

found by PMD

Change-Id: I2b48f35d252d6e914c2a18a2c175b075a9d3ac0f
Reviewed-on: https://gerrit.libreoffice.org/13099
Reviewed-by: Noel Grandin <noelgrandin@gmail.com>
Tested-by: Noel Grandin <noelgrandin@gmail.com>