Groovy supports multi-dispatch, if you needed to encapsulate a generic type, the compile would dynamically resolve that type correctly. See my example in Java (which has method overloading, but not MD)

What would multi-dispatch do differently???

the difference is that overloading works on compile time types but dispatch works on runtime types. This matters because when you write a generic algorithm, you don't know the type, so don't get the right behavior with overloading (you get the generic fallback).

In Groovy, dynamic dispatch is used. It's the runtime types that matter, as my example makes patently clear.

EDIT: to make it even more obvious there's no difference:

    class Fire{}
    class Water {}
    class Grass {}
    class Ice {}
    
    def eff(Fire f, Grass g) { 'burn' }
    def eff(Fire f, Ice ice) { 'melt' }
    def eff(Water w, Grass g) { 'grow' }
    def eff(Water w, Ice ice) { 'freeze' }
    def eff(a, b) { 'undefined' }
    
    // hide compile-time types
    Object fire = new Fire()
    Object grass = new Grass()
    Object ice = new Ice()
    Object water = new Water()
    
    println eff(fire, grass)
    println eff(fire, ice)
    println eff(water, grass)
    println eff(water, ice)
    
    println eff(ice, water)

Prints:

    burn
    melt
    grow
    freeze
    undefined