I want to know that FOP2 is allowed to develop custom local plugin or not. If yes, How can I do that?. Please give me an example or developer guide.
Any free plugin can be used as a sample as their code is exposed and sometimes commented, look into /var/www/html/fop2/admin/plugins/xxxxx for them.
The fop2 tarball has a plugin directory with a "sampleplugin" that is heavily commented also, you can use that to get an idea as that sample plugin is the only developer guide we have for now.