Mark PaymentFlowExtras as deprecated (#1884)

stripe/src/main/java/com/stripe/android/view/PaymentFlowExtras.kt

@@ -1,11 +1,51 @@
 package com.stripe.android.view
 
+import com.stripe.android.PaymentSessionConfig
+
+/**
+ * See [PaymentSessionConfig.Builder.setShippingInformationValidator] and
+ * [PaymentSessionConfig.Builder.setShippingMethodsFactory]
+ */
 object PaymentFlowExtras {
+    /**
+     * Implement [PaymentSessionConfig.ShippingMethodsFactory.create]
+     */
+    @Deprecated("See PaymentSessionConfig.ShippingMethodsFactory")
     const val EXTRA_DEFAULT_SHIPPING_METHOD: String = "default_shipping_method"
+
+    /**
+     * Implement [PaymentSessionConfig.ShippingInformationValidator.isValid]
+     */
+    @Deprecated("See PaymentSessionConfig.ShippingInformationValidator")
     const val EXTRA_IS_SHIPPING_INFO_VALID: String = "shipping_is_shipping_info_valid"
+
+    /**
+     * Implement [PaymentSessionConfig.ShippingInformationValidator]
+     */
+    @Deprecated("See PaymentSessionConfig.ShippingInformationValidator")
     const val EXTRA_SHIPPING_INFO_DATA: String = "shipping_info_data"
+
+    /**
+     * Implement [PaymentSessionConfig.ShippingInformationValidator.getErrorMessage]
+     */
+    @Deprecated("See PaymentSessionConfig.ShippingInformationValidator")
     const val EXTRA_SHIPPING_INFO_ERROR: String = "shipping_info_error"
+
+    /**
+     * Implement [PaymentSessionConfig.ShippingInformationValidator]
+     */
+    @Deprecated("See PaymentSessionConfig.ShippingInformationValidator")
     const val EVENT_SHIPPING_INFO_PROCESSED: String = "shipping_info_processed"
+
+    /**
+     * Implement [PaymentSessionConfig.ShippingInformationValidator]
+     */
+    @Deprecated("See PaymentSessionConfig.ShippingInformationValidator")
     const val EVENT_SHIPPING_INFO_SUBMITTED: String = "shipping_info_submitted"
+
+    /**
+     * Implement [PaymentSessionConfig.ShippingMethodsFactory.create]
+     */
+    @Deprecated("See PaymentSessionConfig.ShippingMethodsFactory")
     const val EXTRA_VALID_SHIPPING_METHODS: String = "valid_shipping_methods"
 }