I wouldn't normally make method arguments final; arguments are passed by value, if you change the variable, it will not change the original variable in the calling method - so it doesn't really make sense to make arguments final.
There is one case in which you might want to do it: if you need to use the argument in an anonymous inner class. For a local variable (or argument) to be used in an anonymous inner class, it must be final. For example:
It is often unnecessary, but it can't do any harm to declare arguments final. That simply means you are promising the compiler you won't re-assign them in the method. Usually unnecessary (except when required for an anonymous inner class).