title: Generating code with maven-jaxb2-plugin does not work with the same configuration after v0.12.0
body: <p>The same pom.xml is working with maven-jaxb2-plugin v0.11 but not with v0.12.</p>
  
  <pre><code>        &lt;plugin&gt;
              &lt;groupId&gt;org.jvnet.jaxb2.maven2&lt;/groupId&gt;
              &lt;artifactId&gt;maven-jaxb2-plugin&lt;/artifactId&gt;
              &lt;executions&gt;
                  &lt;execution&gt;
                      &lt;goals&gt;
                          &lt;goal&gt;generate&lt;/goal&gt;
                      &lt;/goals&gt;
                  &lt;/execution&gt;
              &lt;/executions&gt;
              &lt;configuration&gt;
                  &lt;extension&gt;true&lt;/extension&gt;
                  &lt;schemaDirectory&gt;${basedir}/src/wsdl&lt;/schemaDirectory&gt;
                  &lt;schemaIncludes&gt;
                      &lt;schemaInclude&gt;*.wsdl&lt;/schemaInclude&gt;
                  &lt;/schemaIncludes&gt;
                  &lt;bindingDirectory&gt;${basedir}/src/jaxws/&lt;/bindingDirectory&gt;
                  &lt;generateDirectory&gt;${basedir}/target/jaxws/java&lt;/generateDirectory&gt;
                  &lt;strict&gt;false&lt;/strict&gt;                  
                  &lt;verbose&gt;true&lt;/verbose&gt;
                  &lt;forceRegenerate&gt;true&lt;/forceRegenerate&gt;
                  &lt;args&gt;
                      &lt;arg&gt;-Xfluent-api&lt;/arg&gt;
                  &lt;/args&gt;
                  &lt;plugins&gt;
                      &lt;plugin&gt;
                          &lt;groupId&gt;org.jvnet.jaxb2_commons&lt;/groupId&gt;
                          &lt;artifactId&gt;jaxb2-fluent-api&lt;/artifactId&gt;
                          &lt;version&gt;3.0&lt;/version&gt;
                      &lt;/plugin&gt;
                  &lt;/plugins&gt;
              &lt;/configuration&gt;
          &lt;/plugin&gt;
  </code></pre>
  
  <p>The reason is because after the fix#23 null is returned rather than "systemId" in the MavenCatalogResolver.java (line:64)</p>
  
  <pre><code>Caused by: java.lang.NullPointerException
      at java.net.URI$Parser.parse(URI.java:3003)
      at java.net.URI.&lt;init&gt;(URI.java:578)
      at org.jvnet.jaxb2.maven2.resolver.tools.MavenCatalogResolver.getResolvedEntity(MavenCatalogResolver.java:64) at com.sun.org.apache.xml.internal.resolver.tools.CatalogResolver.resolveEntity(CatalogResolver.java:192)
  </code></pre>
  
  <p>What would be the right configuration for my pom.xml in order to make it work?</p>