This is the Eclipse log:
!ENTRY org.eclipse.core.jobs 4 2 2012-05-30 11:50:29.266
!MESSAGE An internal error occurred during: "Updating Maven Configuration".
!STACK 0
org.eclipse.core.runtime.AssertionFailedException: assertion failed: No web content folder was found in project gwt-utility-example
at org.eclipse.core.runtime.Assert.isTrue(Assert.java:110)
at org.jboss.tools.maven.gwt.GWTProjectConfigurator.getWebContentFolder(GWTProjectConfigurator.java:155)
at org.jboss.tools.maven.gwt.GWTProjectConfigurator.configure(GWTProjectConfigurator.java:71)
at org.eclipse.m2e.core.project.configurator.AbstractLifecycleMapping.configure(AbstractLifecycleMapping.java:72)
at org.eclipse.m2e.core.internal.project.ProjectConfigurationManager.updateProjectConfiguration(ProjectConfigurationManager.java:302)
at org.eclipse.m2e.core.internal.project.ProjectConfigurationManager.updateProjectConfiguration(ProjectConfigurationManager.java:277)
at org.eclipse.m2e.core.ui.internal.UpdateConfigurationJob.runInWorkspace(UpdateConfigurationJob.java:87)
at org.eclipse.core.internal.resources.InternalWorkspaceJob.run(InternalWorkspaceJob.java:38)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:54)
Looking at the code of GWTProjectConfigurator it seems that the presence of the gwt-maven-plugin leads to the assumption that the project must be a web project.
Please see https://source.jboss.org/changelog/JBossTools?cs=40394, work done for issue https://issues.jboss.org/browse/JBIDE-11224.