Generating XSD schemas from JAXB types in Maven?

I'm trying to basically generate XSD schemas from my model classes annotated in JAXB using a Maven plugin. Here's the relevant code in my POM:

<plugin>
    <groupId>com.sun.tools.jxc.maven2</groupId>
    <artifactId>maven-jaxb-schemagen-plugin</artifactId>
    <version>1.2</version>
    <executions>
        <execution>
            <phase>generate-resources</phase>
            <goals>
                <goal>generate</goal>
            </goals>
        </execution>
    </executions>

    <configuration>
        <project>${project}</project>
        <destdir>${project.build.directory}/schemas</destdir>
        <srcdir>${project.build.sourceDirectory}/com/floodstream/wowza/mastercontrol/model</srcdir>
        <verbose>true</verbose>
    </configuration>

    <dependencies>
        <dependency>
            <groupId>javax.xml.bind</groupId>
            <artifactId>jaxb-api</artifactId>
            <version>2.2</version>
        </dependency>
        <dependency>
            <groupId>com.sun.xml.bind</groupId>
            <artifactId>jaxb-xjc</artifactId>
            <version>2.2</version>
        </dependency>
        <dependency>
            <groupId>com.sun.xml.bind</groupId>
            <artifactId>jaxb-impl</artifactId>
            <version>2.2</version>
        </dependency>
        <dependency>
            <groupId>com.sun.xml.bind</groupId>
            <artifactId>jaxb-xjc</artifactId>
            <version>2.2</version>
        </dependency>
    </dependencies>
</plugin>

<!-- other stuff omitted for brevity -->

<pluginRepository>
    <id>maven-repository.dev.java.net</id>
    <name>Java.net Maven 2 Repository</name>
    <url>http://download.java.net/maven/2</url>
</pluginRepository>

I get the following error:

[ERROR] FATAL ERROR
[INFO] ------------------------------------------------------------------------
[INFO] org/apache/tools/ant/taskdefs/Javac
org.apache.tools.ant.taskdefs.Javac
[INFO] ------------------------------------------------------------------------
[INFO] Trace
java.lang.NoClassDefFoundError: org/apache/tools/ant/taskdefs/Javac
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
        at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
        at org.codehaus.classworlds.RealmClassLoader.loadClassDirect(RealmClassLoader.java:195)
        at org.codehaus.classworlds.DefaultClassRealm.loadClass(DefaultClassRealm.java:255)
        at org.codehaus.classworlds.RealmClassLoader.loadClass(RealmClassLoader.java:214)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
        at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
        at org.codehaus.classworlds.RealmClassLoader.loadClassDirect(RealmClassLoader.java:195)
        at org.codehaus.classworlds.DefaultClassRealm.loadClass(DefaultClassRealm.java:255)
        at org.codehaus.classworlds.RealmClassLoader.loadClass(RealmClassLoader.java:214)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:634)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
        at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
        at org.codehaus.classworlds.RealmClassLoader.loadClassDirect(RealmClassLoader.java:195)
        at org.codehaus.classworlds.DefaultClassRealm.loadClass(DefaultClassRealm.java:255)
        at org.codehaus.classworlds.RealmClassLoader.loadClass(RealmClassLoader.java:214)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
        at com.sun.tools.jxc.maven2.SchemaGenMojo.execute(SchemaGenMojo.java:143)
        at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:490)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:694)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLifecycle(DefaultLifecycleExecutor.java:556)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:535)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:387)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:348)
        at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:180)
        at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:328)
        at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:138)
        at org.apache.maven.cli.MavenCli.main(MavenCli.java:362)
        at org.apache.maven.cli.compat.CompatibleMain.main(CompatibleMain.java:60)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:616)
        at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
        at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
        at org.codehaus.classworlds.Launcher.mainWithExitCode(Launcher.java:430)
        at org.codehaus.classworlds.Launcher.main(Launcher.java:375)
Caused by: java.lang.ClassNotFoundException: org.apache.tools.ant.taskdefs.Javac
        at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
        at org.codehaus.classworlds.RealmClassLoader.loadClassDirect(RealmClassLoader.java:195)
        at org.codehaus.classworlds.DefaultClassRealm.loadClass(DefaultClassRealm.java:255)
        at org.codehaus.classworlds.DefaultClassRealm.loadClass(DefaultClassRealm.java:274)
        at org.codehaus.classworlds.RealmClassLoader.loadClass(RealmClassLoader.java:214)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
        ... 59 more
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 4 seconds
[INFO] Finished at: Tue Aug 30 17:40:29 PDT 2011
[INFO] Final Memory: 16M/170M
[INFO] ------------------------------------------------------------------------

Here's the win:

<plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>jaxb2-maven-plugin</artifactId>
    <version>1.3.1</version>
    <executions>
        <execution>
            <goals>
                <goal>schemagen</goal>
            </goals>
            <phase>generate-resources</phase>
            <configuration>
                <includes>
                    <include>com/myproject/model/*.java</include>
                </includes>
                <outputDirectory>${project.build.directory}/schemas</outputDirectory>
            </configuration>
        </execution>
    </executions>
</plugin>