Currently the plugin uses and has been tested with GWT 2.8.1. This version is defined in the plugin dependencies, so if you want another (newer) version you must change your pom as follows:
<project>
<properties>
<gwt.version>your preferred GWT SDK version here</gwt.version>
</properties>
[...]
<build>
<plugins>
[...]
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>gwt-maven-plugin</artifactId>
<version>2.8.1</version>
<dependencies>
<dependency>
<groupId>com.google.gwt</groupId>
<artifactId>gwt-user</artifactId>
<version>2.8.1</version>
</dependency>
<dependency>
<groupId>com.google.gwt</groupId>
<artifactId>gwt-dev</artifactId>
<version>2.8.1</version>
</dependency>
<dependency>
<groupId>com.google.gwt</groupId>
<artifactId>gwt-codeserver</artifactId>
<version>2.8.1</version>
</dependency>
</dependencies>
</plugin>
[...]
</plugins>
</build>
[...]
</project>Note that starting with 2.5.0-rc1, the plugin depends on gwt-user, gwt-dev and gwt-codeserver. Previous versions depended on gwt-user, gwt-dev and gwt-servlet. All dependencies should be overridden.