java type inference

interface Foo<T> {
    void doFoo(T arg);
}

class Bar<T> {
    private T arg;
    private Foo<T> foo;

    Bar(T arg, Foo<T> foo) {
        this.arg = arg;
        this.foo = foo;
    }

    void doBar(){
        this.foo.doFoo(this.arg);
    }
}

class FooImpl<T> implements Foo<Supplier<T>> {
    public void doFoo(Supplier<T> arg) {
        System.out.println(arg.get());
    }
}

public static void main(String... args) {
    new Bar<>(
        "hello, world!",
        new FooImpl<>()
    ).doBar();
}