diacritical characters (polish letters) - problem

How to display polish characters in Vaadin framework? I using Spring framework and I have got MySQL database which administrate from Phpmyadmin level.

Hi, this looks like a character encoding mismatch between Vaadin and MySQL. Vaadin uses the UTF-8 character encoding for everything, so please first ensure that your MySQL database (and possibly Phpmyadmin) is also configured to use UTF-8.

From Apache Tomcat log:

12:10:59,716 DEBUG EntityPrinter:121 - pl.controlprocess.flota.entities.Message{sendDate=2013-06-03 10:37:57.0, message=Wiadomo??, id=8, isArchive=false, toUser=pl.controlprocess.flota.entities.User#1, fromUser=pl.controlprocess.flota.entities.User#1, header=Wiadomo??}

My problem is solved:

In persistence.xml file we must add: