Following with existing infrastructure from MVC 3.2.
Otherwise to get `matrixVariables` we need to have this SpEL:
`expression="#requestAttributes['org.springframework.web.servlet.HandlerMapping.matrixVariables']"`
or with MVC 3.2:
`expression="#requestAttributes[T(org.springframework.web.servlet.HandlerMapping).MATRIX_VARIABLES_ATTRIBUTE]"`
Take a look MVC spec: http://docs.spring.io/spring/docs/3.2.4.RELEASE/spring-framework-reference/html/mvc.html#mvc-ann-matrix-variables