Mysql REST API problem with unicode

hello there

I deployed orbeon 3.9.0 CE on jboss 5. after several days of trying now I can use mysql as persistence layer.
I have to design form in persian language (not only form data is in persian but also label of form elements is in persian). The problem is my persian labels is turned to "???" after saving and publishing the designed form (with form builder). I also check the orbeon_form_data table in mysql and i found out that the persian form lables and data are store as "?" in database.

I googled the topic but i cannot find anything useful. I guess the problem is related to mysql REST API which has problem with unicode because when I use exist as persistence layer, my persian characters are shown and stored correctly.
Also I have to say I set database character "utf8_general_ci" set by this command:

alter database character set utf8 collate utf8_general_ci;

Thanks in advance