golang how to access promoted type

I have a 'common' structure promoted within two specific structures. For example:

type common struct {
    name string
}

type apple struct {
    common
}

type orange struct {
    common
}

Details specific to apple and orange are omitted.

I have a type-specific map of each, e.g., map[string]*apple and map[string]*orange.

I am trying to make a single function that can extract the common pointers. From what I've tried so far, reflection appears required.

My function is:

func getFruitArray(theMap interface{}) []*common {
    m := reflect.ValueOf(theMap)
    cf := make([]*common, 0, m.Len())
    for _, mk := range m.MapKeys() {
        v := m.MapIndex(mk)
        cf = append(cf, v.Interface().(*common))
    }

    return cf
}

This function fails at cf = append(cf, v.Interface().(*common)) with:

panic: interface conversion: interface {} is *main.apple, not *main.common

Is there a way to access the promoted struct common without specifically referencing apple or orange in this function?

playground example