javaunohelper: If statement is redundant

Change-Id: I204e3755cf07c7bb9634d02913e893179d6e81e8
Reviewed-on: https://gerrit.libreoffice.org/10640
Reviewed-by: David Tardon <dtardon@redhat.com>
Tested-by: David Tardon <dtardon@redhat.com>