Right now the Spiffy UI Maven plugin uses the gwt-maven-plugin version 2.2 which depends on GWT version 2.2. This causes a compiler error when you depend on GWT 2.3 and makes it very difficult for Spiffy UI users to use GWT version 2.3.

The Spiffy UI Maven plugin should use gwt-maven-plugin version 2.3 to use the latest GWT compiler.

Fixed in revision 1351 by changing the dependency on version 2.3 of the gwt-maven-plugin.

I meant to mark this issue as fixed with comment 1.