Kotlin singleton converted from Java

Singleton.kt

<!-- Copyright 2019 Google LLC.
SPDX-License-Identifier: Apache-2.0 -->

class Singleton private constructor() {
    private var count = 0
    fun count(): Int {
        return count++
    }

    companion object {
        private var INSTANCE: Singleton? = null// Double checked

        // Single Checked
        val instance: Singleton?
            get() {
                if (INSTANCE == null) { // Single Checked
                    synchronized(Singleton::class.java) {
                        if (INSTANCE == null) { // Double checked
                            INSTANCE =
                                Singleton()
                        }
                    }
                }
                return INSTANCE
            }
    }
}