Now you have to find out where these empty requests came from. They will probably not send by GWT itself. Maybe its a browser issue or a proxy in between your app and your server or someone just tries to fool your server with hand crafted POST requests.
You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group.
To unsubscribe from this group and stop receiving emails from it, send an email to email@example.com.
To post to this group, send email to firstname.lastname@example.org.
Visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.
For more options, visit https://groups.google.com/groups/opt_out.