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.data/src/org/eclipse/birt/data/engine/impl/PreparedQuery.java
prepareExpression( ce.getOperand2(), groupLevel, cx, reg );
	    	 
	    	
	    	expr.setHandle( ce );
	    }
	    else if ( expr instanceof IExpressionCollection )
		{
			IExpressionCollection ce = (IExpressionCollection) expr;
			Object[] exprs = ce.getExpressions( ).toArray( );
			for ( int i = 0; i < exprs.length; i++ )
			{
				prepareExpression( (IBaseExpression)exprs[i],
						groupLevel,
						cx,
						reg );
			}
		}
	    else
	    {
	    	
	    	assert false;
	    }
	}
	/**
	 * When a TopN/TopPercent/BottomN/BottomPercent ConditionalExpression is
	 * set, transform it to
	 * Total.TopN/Total.TopPercent/Total.BottomN/Total.BottomPercent
	 * aggregations with "isTrue" operator.
	 * 
	 * @param ce