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
List properties = handle.getUserProperties( );
		for ( int i = 0; i < properties.size( ); i++ )
		{
			UserPropertyDefn p = (UserPropertyDefn) properties.get( i );
			paramGroup.addUserProperty( p.getName( ), handle.getProperty( p
					.getName( ) ) );
		}
		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 visitScalarParameter( ScalarParameterHandle handle )
	{
		assert ( handle.getName( ) != null );
		
		ScalarParameterDefn scalarParameter = new ScalarParameterDefn( );
		scalarParameter.setHandle( handle );
		scalarParameter.setParameterType( IParameterDefnBase.SCALAR_PARAMETER );
		scalarParameter.setName( handle.getName( ) );
		
		List properties = handle.getUserProperties( );
		for ( int i = 0; i < properties.size( ); i++ )