How do I tell the maven-jaxb2-plugin to run xjc on

I'm using the maven-jaxb2-plugin and my .xsd files are in a maven dependency. The documentation shows that you specify a .xsd in a maven dependency like this

<schema>
    <!-- Specifies a schema from the Maven artifact. -->
    <dependencyResource>
        <groupId>org.jvnet.jaxb2.maven2</groupId>
        <artifactId>maven-jaxb2-plugin-tests-po</artifactId>
        <!--  Version of the artifact. May be omitted.
        The plugin will then try to find the version using
        the dependencyManagement and dependencies of the project. -->
        <version>${project.version}</version>
        <!-- Path of the resource within the artifact. -->
        <resource>purchaseorder.xsd</resource>
    </dependencyResource>
</schema>

I want to run xjc on all .xsd files in the dependent .jar file. The .xsd files are in different directories within the .jar file. I've tried this

<resource>**/*.xsd</resource>

but that fails with this Exception

org.xml.sax.SAXParseException; schema_reference.4: Failed to read schema document 'maven:com.dg:XSD:jar::5.0.3.4!/**/*.xsd', because 1) could not find the document; 2) the document could not be read; 3) the root element of the document is not <xsd:schema>.

Is there a way to specify all .xsd files in a mvn dependency when they are in different directories?

Also, can xjc sort out a dependency tree on a group of .xsd files where one .xsd file depends on another, which may depend on another, ...?

Thanks.

Is there a way to specify all .xsd files in a mvn dependency when they are in different directories?

No, at the moment you'll have to specify individual schema files. You don't need to specify all of them, just the "root" ones. Feel free to file an issue for that.