I have the problem just like the title. I know there is a `@RequesetParam` in spring mvc, it has a parameter `required=false`. But it failed when try to use it.

Actually I found the `@RequestParam` is useless. According to my trying, It always be O.K. using `@RequestParam(value="root", required=true)` where the URL is with/without `value=some value except blank`. 
So, I don't know what totally the `required=true` is. Then, whichever the `required=false` or `required=true`is, it throws exception with URL parameter like `...&root=`.

And my HandlerMapping & AdapterMapping are RequestMappingHandlerMapping and RequestMappingHandlerAdapter

the version of spring mvc is 3.2.4

Please tell me what's going on with the spring mvc?

Thanks advance:)