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
{
			for ( int i = 0; i < parameters.size( ); i++ )
			{
				ScalarParameterHandle parameter = null;
				if ( parameters.get( i ) instanceof ScalarParameterHandle )
				{
					parameter = ( (ScalarParameterHandle) parameters.get( i ) );
				}
				
				String curName = null;
				if ( parameter != null && parameter.getName( ) != null )
				{
					curName = parameter.getName( ) + "_" + parameter.getID( ); 
				}
				
				if ( curName != null
						&& curName.equalsIgnoreCase( configVarName ) )
				{
					paramName = parameter.getName( );
					break;
				}
			}
		}
		return paramName;
	}
	protected IViewerReportDesignHandle getDesignHandle(
			HttpServletRequest request )
	{
		IViewerReportDesignHandle design = null;
		IReportRunnable reportRunnable = null;