auto disposable extension for ViewModel

ViewModel.kt

package androidx.lifecycle

import io.reactivex.disposables.CompositeDisposable
import io.reactivex.disposables.Disposable
import java.io.Closeable

private const val JOB_KEY = "io.reactivex.disposables.Disposable.JOB_KEY"

val ViewModel.disposable: CompositeDisposable
    get() {
        val disposable: Disposable? = getTag(JOB_KEY)
        if (disposable is CompositeDisposable) {
            return disposable
        }
        return setTagIfAbsent(JOB_KEY, CloseableDisposable()).disposable
    }

private class CloseableDisposable(
        val disposable: CompositeDisposable = CompositeDisposable()
) : Closeable, Disposable by disposable {
    override fun close() {
        disposable.clear()
    }
}