Error on build SOAP project using jaxws-maven-plugin

Question

Before update the project from java 1.6 to java 1.8, and the maven plugin jaxws-maven-plugin from 2.3 to 2.3.1-b20150201.1248, I'm getting the error:

Failed to execute goal org.jvnet.jax-ws-commons:jaxws-maven-plugin:2.3.1-b20150201.1248:wsgen on project <project name> Mojo failed - check output

This is my plugin:

`<plugin>
  <groupId>org.jvnet.jax-ws-commons</groupId>
  <artifactId>jaxws-maven-plugin</artifactId>
  <version>2.3.1-b20150201.1248</version>
  <executions>
    <execution>
    <goals>
      <goal>wsgen</goal>
    </goals>
    <configuration>
      <sei>
        <my package and class here>
      </sei>
      <genWsdl>true</genWsdl>
      <encoding>UTF-8</encoding>
      <verbose>true</verbose>
      <keep>true</keep>
       </configuration>
       <phase>package</phase>
   </execution>
 </executions>
</plugin>`

I dont know what i should do.