Exception while dispatching incoming RPC call: javax.servlet.ServletException: Character Encoding is null

I get this exception when i deploy on my websphere server. It works
fine in tomcat. How is the encoding becoming null here?

Exception while dispatching incoming RPC call:
javax.servlet.ServletException: Character Encoding is '(null)'.
Expected 'UTF-8'
at
com.google.gwt.user.server.rpc.RPCServletUtils.checkCharacterEncodingIgnoreCase(RPCServletUtils.java:
391)
at
com.google.gwt.user.server.rpc.RPCServletUtils.readContent(RPCServletUtils.java:
163)
at
com.google.gwt.user.server.rpc.RPCServletUtils.readContentAsGwtRpc(RPCServletUtils.java:
205)
at
com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.readContent(AbstractRemoteServiceServlet.java:
182)
at
com.google.gwt.user.server.rpc.RemoteServiceServlet.processPost(RemoteServiceServlet.java:
239)
at
com.google.gwt.user.server.rpc.AbstractRemoteServiceServlet.doPost(AbstractRemoteServiceServlet.java:
62)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:
763)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:
856)

--
You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group.
To post to this group, send email to google-web-toolkit@googlegroups.com.
To unsubscribe from this group, send email to google-web-toolkit+unsubscribe@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.