docs: add comment for arbitrary value fields

Author: stainless-app[bot]

orb-java-core/src/main/kotlin/com/withorb/api/models/ChangedSubscriptionResources.kt

@@ -790,6 +790,11 @@ private constructor(
          * This field is deprecated in favor of `discounts`. If a `discounts` list is provided, the
          * first discount in the list will be returned. If the list is empty, `None` will be
          * returned.
+         *
+         * This arbitrary value can be deserialized into a custom type using the `convert` method:
+         * ```java
+         * MyClass myObject = createdInvoice.discount().convert(MyClass.class);
+         * ```
          */
         @Deprecated("deprecated")
         @JsonProperty("discount")

orb-java-core/src/main/kotlin/com/withorb/api/models/Invoice.kt

@@ -450,6 +450,11 @@ private constructor(
     /**
      * This field is deprecated in favor of `discounts`. If a `discounts` list is provided, the
      * first discount in the list will be returned. If the list is empty, `None` will be returned.
+     *
+     * This arbitrary value can be deserialized into a custom type using the `convert` method:
+     * ```java
+     * MyClass myObject = invoice.discount().convert(MyClass.class);
+     * ```
      */
     @Deprecated("deprecated")
     @JsonProperty("discount")

orb-java-core/src/main/kotlin/com/withorb/api/models/InvoiceFetchUpcomingResponse.kt

@@ -443,6 +443,11 @@ private constructor(
     /**
      * This field is deprecated in favor of `discounts`. If a `discounts` list is provided, the
      * first discount in the list will be returned. If the list is empty, `None` will be returned.
+     *
+     * This arbitrary value can be deserialized into a custom type using the `convert` method:
+     * ```java
+     * MyClass myObject = invoiceFetchUpcomingResponse.discount().convert(MyClass.class);
+     * ```
      */
     @Deprecated("deprecated")
     @JsonProperty("discount")