Bug 153412 Change parameter type will cause preview fail
Description: Change parameter type will cause preview fail Steps to reproduce: 1. New a report paramter, string, text-box, default value is abc. 2. Drag the parameter to Layout and preview. 3. Change the parameter's type to integer, list-box, add a value 1 4. Preview Expected result: No errors. Actual result: The value "abc" is invalid with the type "integer".
UI/org.eclipse.birt.report.designer.ui.preview/src/org/eclipse/birt/report/designer/ui/preview/editors/ReportPreviewFormPage.java
/**
	 * Get parameter values from config file.
	 * 
	 * @return Map
	 */
	private Map getConfigVars( )
	{
		HashMap configVars = new HashMap( );
		
		String configFileName = getConfigFileName( this.getFileUri( ) );
		if ( configFileName == null )
			return configVars;
		ReportDesignHandle handle = null;
		try
		{
			
			SessionHandle sessionHandle = SessionHandleAdapter.getInstance( )
					.getSessionHandle( );
			File configFile = new File( configFileName );
			
			if ( configFile != null
					&& configFile.exists( )
					&& configFile.isFile( ) )
			{
				handle = sessionHandle.openDesign( configFileName );
				if ( handle != null )
				{
					
					Iterator it = handle.configVariablesIterator( );
					while ( it != null && it.hasNext( ) )