Ok, I have got the reason for the exception. I have got (cascade={CascadeType.PERSIST}) forgotten.
But how could I transfer for example the company object to my GWT Client Side? -- You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. To view this discussion on the web visit https://groups.google.com/d/msg/google-web-toolkit/-/cg0dTCK_dj4J. To post to this group, send email to google-web-toolkit@googlegroups.com. To unsubscribe from this group, send email to google-web-toolkit+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.