How to create and apply a UML2 stereo-type using EMF in a standalone app?

I have written the sample application below to create an EJB stereotype an apply it to the TimeEntry class:

import java.io.File;
import org.eclipse.emf.common.util.URI;
import org.eclipse.emf.ecore.resource.Resource;
import org.eclipse.emf.ecore.resource.Resource.Factory;
import org.eclipse.emf.ecore.resource.ResourceSet;
import org.eclipse.emf.ecore.resource.impl.ResourceSetImpl;
import org.eclipse.emf.ecore.util.EcoreUtil;
import org.eclipse.uml2.uml.*;
import org.eclipse.uml2.uml.Class;
import org.eclipse.uml2.uml.Package;
import org.eclipse.uml2.uml.UMLPackage.Literals;
import org.eclipse.uml2.uml.resource.UMLResource;

public class SampleProfile
{

  private static final ResourceSet RESOURCE_SET = new ResourceSetImpl();

  public static void main( String[] args ) throws Exception
  {

    Factory.Registry.INSTANCE.getExtensionToFactoryMap().put(
      UMLResource.FILE_EXTENSION,
      UMLResource.Factory.INSTANCE
    );

    final Model umlMetamodel = (Model) loadPackage( UMLResource.UML_METAMODEL_URI );

    final Model sampleModel = UMLFactory.eINSTANCE.createModel();
    sampleModel.setName( "Sample Model" );

    final Profile sampleProfile = UMLFactory.eINSTANCE.createProfile();
    sampleProfile.setName( "Sample Profile" );

    final Stereotype ejbStereo = sampleProfile.createOwnedStereotype( "EJB" );
    extendMetaclass( umlMetamodel, sampleProfile, "Class", ejbStereo );

    sampleProfile.define();

    final Package samplePackage = sampleModel.createNestedPackage( "sample" );
    samplePackage.applyProfile( sampleProfile );

    final Class sampleClass = samplePackage.createOwnedClass( "TimeEntry", false );
    sampleClass.applyStereotype( ejbStereo );

    final File outputFile = new File( "sample_model.uml" );
    final URI outputUri = URI.createFileURI( outputFile.getAbsolutePath() );
    final Resource resource = RESOURCE_SET.createResource( outputUri );
    resource.getContents().add( sampleModel );
    resource.getContents().add( sampleProfile );
    resource.save( null );
  }

  private static Package loadPackage( final String uri )
  {
    System.out.println( "uri = " + uri );
    final Resource resource = RESOURCE_SET.getResource( URI.createURI( uri ), true );
    EcoreUtil.resolveAll( resource );
    return (org.eclipse.uml2.uml.Package) EcoreUtil.getObjectByType( resource.getContents(), Literals.PACKAGE );
  }

  private static void extendMetaclass( final Model umlMetamodel,
                                       final Profile profile,
                                       final String name,
                                       final Stereotype stereotype )
  {
    stereotype.createExtension( referenceMetaclass( umlMetamodel, profile, name ), true );
  }

  private static org.eclipse.uml2.uml.Class referenceMetaclass( final Model umlMetamodel,
                                                                final Profile profile,
                                                                final String name )
  {
    final Class metaclass = (Class) umlMetamodel.getOwnedType( name );
    profile.createMetaclassReference( metaclass );
    return metaclass;
  }
}

However running the application, I get this error message in the console:

uri = pathmap://UML_METAMODELS/UML.metamodel.uml
Exception in thread "main" org.eclipse.emf.ecore.resource.impl.ResourceSetImpl$1DiagnosticWrappedException: java.net.MalformedURLException: unknown protocol: pathmap
    at org.eclipse.emf.ecore.resource.impl.ResourceSetImpl.handleDemandLoadException(ResourceSetImpl.java:315)
    at org.eclipse.emf.ecore.resource.impl.ResourceSetImpl.demandLoadHelper(ResourceSetImpl.java:274)
    at org.eclipse.emf.ecore.resource.impl.ResourceSetImpl.getResource(ResourceSetImpl.java:397)

Any ideas what's probably wrong with my code and how this problem can be solved? The application is a command-line app that runs outside Eclipse.

I found the answer to this question on the EMF/UML2 forum: Getting null for the meta model.