如何为zend framework 2 restful route创建一个可选的route参数

I'm working with zend framework 2 and I need to create an optional parameter for a route segment that also has two required parameters. Below is a snippet from the module.config.php describing the route. My understanding is that in ZF2 an optional route parameter can be created by using the I'm working with zend framework 2 and I need to