Bug 213907 Provide a copy constructor for SubqueryDefinition.
Engine need a copy constructor to generate a SubqueryDefinition from an ISubqueryDefinition and change the name of the query.
data/org.eclipse.birt.report.data.adapter/src/org/eclipse/birt/report/data/adapter/impl/DataRequestSessionImpl.java
{
	
	private DataEngineImpl dataEngine;
	private IModelAdapter modelAdaptor;
	private DataSessionContext sessionContext;
	private Map cubeHandleMap;
	private StopSign stopSign;
	private Set dataSetCache;
	/**
	 * Constructs the data request session with the provided session context
	 * information.
	 * 
	 * @param context
	 * @throws BirtException
	 */
	public DataRequestSessionImpl( DataSessionContext context )
			throws BirtException
	{