'should be called from the activity
Sub LaunchBillingFlow(sku As SkuDetails, OldSku As String, PurchaseToken As String) As BillingResult
Dim jo As JavaObject = Starter.billing
Dim BillingClient As JavaObject = jo.GetField("client")
Dim context As JavaObject
context.InitializeContext
Dim BillingFlowParams As JavaObject
BillingFlowParams = BillingFlowParams.InitializeStatic("com.android.billingclient.api.BillingFlowParams") _
.RunMethodJO("newBuilder", Null).RunMethodJO("setSkuDetails", Array(sku)) _
.RunMethodJO("setOldSku", Array(OldSku, PurchaseToken)).RunMethod("build", Null)
Return BillingClient.RunMethod("launchBillingFlow", Array(context, BillingFlowParams))
End Sub