Golang で「interface{}」として渡された匿名構造体のフィールドにアクセスするにはどうすればよいですか?

<code class="go">package main

import (
    "fmt"
    "log"
    "time"
)

type job struct {
    name    string
    action  func()
    custom  interface{}
}

func NewJob(t string, name string, c func(), v interface{}) {
    job := process(t)
    job.name = name
    job.action = c
    job.custom = v

    go func() {
        for {
            job.action()
            time.Sleep(2 * time.Second)
        }
    }()
}

func Custom(name string) interface{} {
    for _, j := range jobs {
        if j.name != name {
            continue
        }
        return j.custom
    }
    return nil
}

func main() {
    NewJob("every 2 second", "pene", func() {
        t := Custom("pene")
        log.Println(t)
    }, struct {
        ID int
    }{
        1,
    })
}</code>

t.ID undefined (type interface {} is interface with no methods)

<code class="go">id := v.(struct{ID int}).ID</code>