kotlin activity_main.xml text reference not valid code example

Example: android kotlin cannot @+id in MainActivity

// in build.gradle(Module:your_app.app) at the begginig of file add last id
// this will allow to call elements from xml in MainActivity.kt file
// for example: button1.setOnClickListener()...

plugins {
    id 'com.android.application'
    id 'kotlin-android'
    id 'kotlin-android-extensions'
}