NullPointerException in org.codehaus.plexus.util.AbstractScanner using dynamic overlay exclusions

[vernyquartara]

Hi everybody,
I want to inform you about a NPE during a Maven build.
I'm using an overlay with dynamic exclusions, as follows:

<overlays>
    <overlay>
        <groupId>it.visura.ecm</groupId>
        <artifactId>visura-ecm-web-static</artifactId>
        <classifier>visura</classifier>
        <excludes>
                <exclude>${overlayExcludes}</exclude>
            </excludes>
    </overlay>
</overlays>

The NPE appears if the value of the overlayExcludes property

1. is not defined or
2. is null or
3. is an empty string ("")

I'm building on a Win7 machine, using Maven 3.0.4 embedded in Eclipse Kelper, jdk1.6.0_45

Here is the fullstacktrace:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-war-plugin:2.4:war (default-war) on project visura-ecm-web: Execution default-war of goal org.apache.maven.plugins:maven-war-plugin:2.4:war failed. NullPointerException -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-war-plugin:2.4:war (default-war) on project visura-ecm-web: Execution default-war of goal org.apache.maven.plugins:maven-war-plugin:2.4:war failed.
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:225)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:320)
at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537)
at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196)
at org.apache.maven.cli.MavenCli.main(MavenCli.java:141)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409)
at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)
Caused by: org.apache.maven.plugin.PluginExecutionException: Execution default-war of goal org.apache.maven.plugins:maven-war-plugin:2.4:war failed.
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:110)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:209)
... 19 more
Caused by: java.lang.NullPointerException
at org.codehaus.plexus.util.AbstractScanner.normalizePattern(AbstractScanner.java:309)
at org.codehaus.plexus.util.AbstractScanner.setExcludes(AbstractScanner.java:296)
at org.apache.maven.plugin.war.packaging.AbstractWarPackagingTask.getFilesToIncludes(AbstractWarPackagingTask.java:394)
at org.apache.maven.plugin.war.packaging.AbstractWarPackagingTask.getFilesToIncludes(AbstractWarPackagingTask.java:375)
at org.apache.maven.plugin.war.packaging.OverlayPackagingTask.performPackaging(OverlayPackagingTask.java:76)
at org.apache.maven.plugin.war.AbstractWarMojo.buildWebapp(AbstractWarMojo.java:505)
at org.apache.maven.plugin.war.AbstractWarMojo.buildExplodedWebapp(AbstractWarMojo.java:433)
at org.apache.maven.plugin.war.WarMojo.performPackaging(WarMojo.java:213)
at org.apache.maven.plugin.war.WarMojo.execute(WarMojo.java:175)
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:101)
... 20 more