Startup Fail because Plugin OSGi can't load bundle's struts.xml throw NullPointerException

see the code of org.apache.struts2.osgi.BundlePackageLoader:

<code>
BundleConfigurationProvider prov = new BundleConfigurationProvider("struts.xml", bundle, bundleContext);
for (PackageConfig pkg : pkgConfigs.values())

{ config.addPackageConfig(pkg.getName(), pkg); }

prov.setObjectFactory(objectFactory);
prov.init(config);
prov.loadPackages();
</code>

because XmlConfigurationProvider need be injected FileManager, but there isn't