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
if ( context == null )
			throw new AdapterException( ResourceConstants.CONEXT_NULL_ERROR );
		dataEngine = (DataEngineImpl)DataEngine.newDataEngine( context.getDataEngineContext( ) );
		modelAdaptor = new ModelAdapter( context );
		sessionContext = context;
		cubeHandleMap = new HashMap( );
		dataSetCache = new HashSet( );
		
		
		
		
		
	}
	/*
	 * @see org.eclipse.birt.report.data.adaptor.impl.IDataRequestSession#defineDataSource(org.eclipse.birt.data.engine.api.IBaseDataSourceDesign)
	 */
	public void defineDataSource( IBaseDataSourceDesign design )
			throws BirtException
	{
		dataEngine.defineDataSource( design );
	}
	/*
	 * @see org.eclipse.birt.report.data.adaptor.impl.IDataRequestSession#defineDataSet(org.eclipse.birt.data.engine.api.IBaseDataSetDesign)
	 */
	public void defineDataSet( IBaseDataSetDesign design ) throws BirtException
	{
		dataEngine.defineDataSet( design );
	}
	/*
	 * @see org.eclipse.birt.report.data.adaptor.api.DataRequestSession#getDataSetMetaData(java.lang.String,