Bug 121687 Exception throws when export data in table which inside a grid cell.
Description: Exception throws when export data in table which inside a grid cell. Steps to reproduce: 1. insert a grid. 2. insert one table to one grid cell. 3. insert another table to the other grid cell. 4. export data in two tables. Expected result: Data are exported. Actual result: Exception in: ReportEngineService.getMetaData( )
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/parser/EngineIRVisitor.java
}
		int size = parameters.getCount( );
		for ( int n = 0; n < size; n++ )
		{
			apply( parameters.get( n ) );
			if ( currentElement != null )
			{
				paramGroup.addParameter( (IParameterDefnBase) currentElement );
			}
		}
		currentElement = paramGroup;
	}
	public void visitCascadingParameterGroup(
			CascadingParameterGroupHandle handle )
	{
		CascadingParameterGroupDefn paramGroup = new CascadingParameterGroupDefn( );
		paramGroup.setHandle( handle );
		paramGroup
				.setParameterType( IParameterDefnBase.CASCADING_PARAMETER_GROUP );
		paramGroup.setName( handle.getName( ) );
		paramGroup.setDisplayName( handle.getDisplayName( ) );
		paramGroup.setDisplayNameKey( handle.getDisplayNameKey( ) );
		paramGroup.setHelpText( handle.getHelpText( ) );
		paramGroup.setHelpTextKey( handle.getHelpTextKey( ) );
		DataSetHandle dset = handle.getDataSet( );
		if ( dset != null )
		{
			paramGroup.setDataSet( dset.getName( ) );
		}
		SlotHandle parameters = handle.getParameters( );