Why is processPurchases() launuched two times in play-billing-samples?

Figure 3 and Code A is from the project play-billing-samples, you can see here.

From the document, launchBillingFlow may be triggered by a button click when the user wants to buy something, then onPurchasesUpdated will be launched.

I'm confused with the comment of override fun onBillingSetupFinished(billingResult: BillingResult){ }, onBillingSetupFinished (include processPurchases()) will be launched when BillingClient has been successfully established.

Normally in a case, I need to init BillingClient first, onBillingSetupFinished be launched, processPurchases() will be launched too, then I click a Buy button, onPurchasesUpdated will be launched, and processPurchases() will be launched again.

Are there some problems with the code?

* Figure 3 -- Server-reliant billing integration with offline access to some entitlements
 *
 *  _____                        _________________
 * |Start|----------------------|launchBillingFlow|
 *  -----                        -----------------
 *                                        |
 *                                  ______v____________
 *                                 |onPurchasesUpdated |
 *                                  -------------------
 *                                 /      |
 *                   ITEM_ALREADY_OWNED   |
 *                               /        |
 *  _____       ________________v__       |
 * |Start|-----|queryPurchasesAsync|      OK
 *  -----       -------------------       |
 *                               \        |
 *                               v________v_______
 *                              |processPurchases |
 *                               -----------------
 *                                        |
 *   

                                 |

Code A

    /**
     * This is the callback for when the connection to the Play [BillingClient] has been successfully
     * established. It might make sense to get [SkuDetails] and [Purchases][Purchase] at this point.
     */
    override fun onBillingSetupFinished(billingResult: BillingResult) {
        when (billingResult.responseCode) {
            BillingClient.BillingResponseCode.OK -> {
                Log.d(LOG_TAG, "onBillingSetupFinished successfully")
                querySkuDetailsAsync(BillingClient.SkuType.INAPP, GameSku.INAPP_SKUS)
                querySkuDetailsAsync(BillingClient.SkuType.SUBS, GameSku.SUBS_SKUS)
                queryPurchasesAsync()
            }
            BillingClient.BillingResponseCode.BILLING_UNAVAILABLE -> {
                //Some apps may choose to make decisions based on this knowledge.
                Log.d(LOG_TAG, billingResult.debugMessage)
            }
            else -> {
                //do nothing. Someone else will connect it through retry policy.
                //May choose to send to server though
                Log.d(LOG_TAG, billingResult.debugMessage)
            }
        }
    }



    override fun onPurchasesUpdated(
            billingResult: BillingResult,
            purchases: MutableList<Purchase>?
    ) {
        when (billingResult.responseCode) {
            BillingClient.BillingResponseCode.OK -> {
                // will handle server verification, consumables, and updating the local cache
                purchases?.apply { processPurchases(this.toSet()) }
            }
            BillingClient.BillingResponseCode.ITEM_ALREADY_OWNED -> {
                // item already owned? call queryPurchasesAsync to verify and process all such items
                Log.d(LOG_TAG, billingResult.debugMessage)
                queryPurchasesAsync()
            }
            BillingClient.BillingResponseCode.SERVICE_DISCONNECTED -> {
                connectToPlayBillingService()
            }
            else -> {
                Log.i(LOG_TAG, billingResult.debugMessage)
            }
        }
    }


   fun queryPurchasesAsync() {
       ...
       processPurchases(purchasesResult)
   }