queryPurchases

override fun onBillingSetupFinished(billingResult: BillingResult) {
    when (billingResult.responseCode) {
        BillingClient.BillingResponseCode.OK -> {
            Log.d(LOG_TAG, "onBillingSetupFinished successfully")
            ...
            queryPurchases()
        }
        ...
    }
}

fun queryPurchases() {
    Log.d(LOG_TAG, "queryPurchasesAsync called")
    val purchasesResult = HashSet<Purchase>()
    var result = playStoreBillingClient.queryPurchases(BillingClient.SkuType.INAPP)
    result?.purchasesList?.let { purchasesResult.addAll(it) }
    
    processPurchases(purchasesResult)
}