let's try and be slightly more clever and use an element contained in the list

Example3g.scala

def exSetAllBeansToFirst(beanList: List[ScalaBean[?]]): Unit =
  val firstBean = beanList.head // bad: don't use head if the list may be empty
  beanList.foreach{bean =>
    bean.setTheA(firstBean.getTheA)
    // ❌ Found:    firstBean.A
    //    Required: bean.A
  }