4063 [in_app_purchase] Added BillingClient.isFeatureSupported (cla: yes, p: in_app_purchase, platform-android)

4071 [in_app_purchase_android] fix version for ‘add payment proxy’: pull/4055 (cla: yes, p: in_app_purchase, platform-android)

4077 [in_app_purchase] billingClient launchPriceChangeConfirmationFlow (cla: yes, waiting for tree to go green, p: in_app_purchase, platform-android)

4079 [in_app_purchase] update gradle tool to 4.1.0 (cla: yes, p: in_app_purchase, platform-android)