Ok, here is the issue.
I made wwrun to have a useful shell
usermod -s /bin/bash wwwrun
Excecuted /opt/libreoffice/program/soffice and said it required java,
Reexecuted the program with --headless.
And then wwwrun was able to run soffice.
But when i tried by the web, then ti didn't worked.
I reseted the server and apache worked correctly.
The issue was, I was reseting the apache wiht apache2ctl restart instead of "system wide restart" with systemctl restart apache.
That was the issue..