Bug 130492 Provide a method to serialize the report with library information.
Currently, when engine generate the report document file, the document does not contain any library information. That will cause many propblem on server side. Model should provide a method to serialize the report with library information to a stream so that the generated report document can contain all information that the report need.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/api/JointDataSetHandle.java
* other element handles.
	 * 
	 * @param module
	 *            the module
	 * @param element
	 *            the model representation of the element
	 */
	public JointDataSetHandle( Module module, JointDataSet element )
	{
		super( module, element );
	}
	/**
	 * Gets the names of the data sets in this joint data set.
	 * 
	 * @return a list of names of data sets in this joint data set.
	 */
	public List getDataSetNames( )
	{
		List dataSetsReferences = getListProperty( JointDataSet.DATA_SETS_PROP );
		if ( dataSetsReferences == null )
		{
			return Collections.EMPTY_LIST;
		}
		List results = new ArrayList( );
		for ( int i = 0; i < dataSetsReferences.size( ); i++ )
		{
			results.add( ( (ElementRefValue) dataSetsReferences.get( i ) )
					.getName( ) );
		}
		return results;