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".
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/context/ViewerAttributeBean.java
}
		this.reportTitle = ParameterAccessor.htmlEncode( title );
		this.__initParameters( request );
	}
	/*
	 * Prepare the report parameters
	 */
	protected void __initParameters( HttpServletRequest request )
			throws Exception
	{
		this.reportDesignHandle = getDesignHandle( request );
		InputOptions options = new InputOptions( );
		options.setOption( InputOptions.OPT_REQUEST, request );
		options.setOption( InputOptions.OPT_LOCALE, locale );
		options.setOption( InputOptions.OPT_RTL, new Boolean( rtl ) );
		
		Collection parameterList = getParameterList( );
		
		if ( this.isDesigner
				&& !IBirtConstants.SERVLET_PATH_FRAMESET
						.equalsIgnoreCase( request.getServletPath( ) ) )
			parseConfigVars( request, parameterList );
		
		this.parametersAsString = getParsedParametersAsString( parameterList,
				request, options );
		
		this.parameterDefList = getReportService( ).getParameterDefinitions(
				this.reportDesignHandle, options, false );
		
		if ( documentInUrl )