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
}
	/**
	 * Adds a data set into this joint data set by name.
	 * 
	 * @param dataSetName
	 *            the name of the data set to be added in.
	 * @throws SemanticException
	 *             if the the value of the item is incorrect.
	 */
	public void addDataSet( String dataSetName ) throws SemanticException
	{
		PropertyCommand command = new PropertyCommand( module, getElement( ) );
		command.addItem(
				(ElementPropertyDefn) getPropertyDefn( DATA_SETS_PROP ),
				dataSetName );
	}
	/**
	 * Removes a data set from this joint data set by name.
	 * 
	 * @param dataSetName
	 *            the name of the data set to be removed.
	 * @throws SemanticException
	 *             if the the value of the item is incorrect.
	 * 
	 */
	public void removeDataSet( String dataSetName ) throws SemanticException
	{
		PropertyCommand command = new PropertyCommand( module, getElement( ) );
		command.removeItem(
				(ElementPropertyDefn) getPropertyDefn( DATA_SETS_PROP ),