This is a known bug (JAX-WS-COMMON-110) that will be fixed in version 2.3.1.
Until jaxws-maven-plugin 2.3.1 is officially released, you may compile it from svn.
svn checkout https://svn.java.net/svn/jax-ws-commons~svn/tags/jaxws-maven-plugin-2.3.1-b03
cd jaxws-maven-plugin-2.3.1-b03
mvn install
And then update your pom.xml to use the 2.3.1-b03 version:
<plugin>
<groupId>org.jvnet.jax-ws-commons</groupId>
<artifactId>jaxws-maven-plugin</artifactId>
<version>2.3.1-b03</version>
...
</plugin>