mvn gwt:run fails with "Unable to start embedded HTTP server"

mvn clean install -DskipTests
cd optaplanner-wb-webapp
mvn gwt:run

[INFO] --- gwt-maven-plugin:2.8.0-rc1:run (default-cli) @ optaplanner-wb-webapp ---
[INFO] create exploded Jetty webapp in /home/ge0ffrey/projects/jboss/just-optaplanner/optaplanner-wb/optaplanner-wb-webapp/src/main/webapp
[INFO] Super Dev Mode starting up
[INFO]    workDir: /tmp/gwt-codeserver-494144656519711515.tmp
[INFO]    Loading Java files in org.optaplanner.workbench.OptaPlannerWorkbench.
[INFO]    Module setup completed in 2904 ms
[INFO] 
[INFO] The code server is ready at http://127.0.0.1:9876/
[INFO] Warning! The CLI is running in a non-modular environment and cannot load commands from management extensions.
[INFO] 08:29:22,005 INFO  [org.jboss.errai.enterprise.rebind.NonGwtEventQualifierSerializerGenerator] (MSC service thread 1-4) Attempting to load org.jboss.errai.cdi.EventQualifierSerializerImpl
[INFO] 08:29:22,008 INFO  [org.jboss.errai.codegen.util.ClassChangeUtil] (MSC service thread 1-4) Searching for class: org.jboss.errai.cdi.EventQualifierSerializerImpl
[INFO] 08:29:22,012 INFO  [org.jboss.errai.codegen.util.ClassChangeUtil] (MSC service thread 1-4) Could not find URL for org.jboss.errai.cdi.EventQualifierSerializerImpl. Attempting to load with context class loader.
[INFO] 08:29:22,012 WARN  [org.jboss.errai.codegen.util.ClassChangeUtil] (MSC service thread 1-4) Could not load org.jboss.errai.cdi.EventQualifierSerializerImpl class.
[INFO] 08:29:22,013 WARN  [org.jboss.errai.enterprise.rebind.NonGwtEventQualifierSerializerGenerator] (MSC service thread 1-4) No org.jboss.errai.cdi.EventQualifierSerializerImpl found on the classpath. Attempting to generate and load.
[INFO] 08:29:22,013 INFO  [org.jboss.errai.enterprise.rebind.NonGwtEventQualifierSerializerGenerator] (MSC service thread 1-4) Generating source for org.jboss.errai.cdi.EventQualifierSerializerImpl...
[INFO] 08:29:22,078 INFO  [org.jboss.errai.common.metadata.MetaDataScanner] (Thread-106) added class scanning extensions: org.jboss.errai.common.metadata.JbossVFsTypeHandler
[INFO] 08:29:22,762 INFO  [org.jboss.errai.reflections.Reflections] (Thread-106) Reflections took 681 ms to scan 111 urls, producing 1273 keys and 9267 values [using 2 cores]
[INFO] 08:29:22,853 INFO  [org.jboss.errai.enterprise.rebind.NonGwtEventQualifierSerializerGenerator] (MSC service thread 1-4) Successfully generated source for org.jboss.errai.cdi.EventQualifierSerializerImpl
[INFO] 08:29:22,853 INFO  [org.jboss.errai.enterprise.rebind.NonGwtEventQualifierSerializerGenerator] (MSC service thread 1-4) Attempting to compile and load org.jboss.errai.cdi.EventQualifierSerializerImpl
[INFO] 08:29:22,853 INFO  [org.jboss.errai.codegen.util.ClassChangeUtil] (MSC service thread 1-4) Compiling and loading org.jboss.errai.cdi.EventQualifierSerializerImpl from source...
[INFO] 08:29:22,864 INFO  [org.jboss.errai.codegen.util.ClassChangeUtil] (MSC service thread 1-4) Using temporary directory for source and class files: /tmp/ge0ffrey/errai/f2e79c2fa3adfd1076dbb7d0d5b547506d4d6/errai.gen/classes/org/jboss/errai/cdi
[INFO] 08:29:22,865 INFO  [org.jboss.errai.codegen.util.ClassChangeUtil] (MSC service thread 1-4) Directory /tmp/ge0ffrey/errai/f2e79c2fa3adfd1076dbb7d0d5b547506d4d6/errai.gen/classes/org/jboss/errai/cdi already exists. Deleting directory and contents (enable debug logging to see deleted files).
[INFO] 08:29:22,865 INFO  [org.jboss.errai.codegen.util.ClassChangeUtil] (MSC service thread 1-4) Writing source file /tmp/ge0ffrey/errai/f2e79c2fa3adfd1076dbb7d0d5b547506d4d6/errai.gen/classes/org/jboss/errai/cdi/EventQualifierSerializerImpl.java...
[INFO] 08:29:22,865 INFO  [org.jboss.errai.codegen.util.ClassChangeUtil] (MSC service thread 1-4) Compiling org.jboss.errai.cdi.EventQualifierSerializerImpl in source file /tmp/ge0ffrey/errai/f2e79c2fa3adfd1076dbb7d0d5b547506d4d6/errai.gen/classes/org/jboss/errai/cdi/EventQualifierSerializerImpl.java...
[INFO] 08:29:24,005 INFO  [org.jboss.errai.codegen.util.ClassChangeUtil] (MSC service thread 1-4) Loading compiled class at /tmp/ge0ffrey/errai/f2e79c2fa3adfd1076dbb7d0d5b547506d4d6/errai.gen/classes/org/jboss/errai/cdi/org/jboss/errai/cdi/EventQualifierSerializerImpl.class...
[INFO] 08:29:24,006 INFO  [org.jboss.errai.enterprise.rebind.NonGwtEventQualifierSerializerGenerator] (MSC service thread 1-4) Successfully generated and loaded org.jboss.errai.cdi.EventQualifierSerializerImpl
[ERROR] Unable to start embedded HTTP server
[ERROR] com.google.gwt.core.ext.UnableToCompleteException: (see previous log entries)
[ERROR]         at org.jboss.errai.cdi.server.gwt.EmbeddedWildFlyLauncher.start(EmbeddedWildFlyLauncher.java:113)
[ERROR]         at com.google.gwt.dev.DevMode.doStartUpServer(DevMode.java:630)
[ERROR]         at com.google.gwt.dev.DevModeBase.startUp(DevModeBase.java:923)
[ERROR]         at com.google.gwt.dev.DevModeBase.run(DevModeBase.java:706)
[ERROR]         at com.google.gwt.dev.DevMode.main(DevMode.java:426)