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
*            HttpServletRequest
	 * @param options
	 *            InputOptions
	 * 
	 * @return Map
	 */
	protected Map getParsedParametersAsString( Collection parameterList,
			HttpServletRequest request, InputOptions options )
			throws ReportServiceException
	{
		Map params = new HashMap( );
		if ( parameterList == null )
			return params;
		for ( Iterator iter = parameterList.iterator( ); iter.hasNext( ); )
		{
			ScalarParameterHandle parameter = null;
			Object parameterObj = iter.next( );
			if ( parameterObj instanceof ScalarParameterHandle )
			{
				parameter = (ScalarParameterHandle) parameterObj;
			}
			
			if ( parameter == null )
				continue;
			String paramName = parameter.getName( );
			String paramValue = getParamValueAsString( request, parameter );
			if ( paramName != null )
				params.put( paramName, paramValue );
		}
		return params;