diff --git a/CHANGELOG.md b/CHANGELOG.md
index ae615843..a70cbf37 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@
 ### Changed
 * Return webhook object with secret when creating a webhook
 * Fixed HTTP method for rotating webhook secret
+* Fixed optional field for `GetAvailabilityResponse`
 
 ## [2.0.0-beta.1] - Released 2023-08-16
 
diff --git a/src/main/kotlin/com/nylas/models/GetAvailabilityResponse.kt b/src/main/kotlin/com/nylas/models/GetAvailabilityResponse.kt
index d50542a5..3994498d 100644
--- a/src/main/kotlin/com/nylas/models/GetAvailabilityResponse.kt
+++ b/src/main/kotlin/com/nylas/models/GetAvailabilityResponse.kt
@@ -11,10 +11,10 @@ data class GetAvailabilityResponse(
    * It will contain the order in which the accounts would be next in line to attend the proposed meeting.
    */
   @Json(name = "order")
-  val order: List<String>,
+  val order: List<String>? = null,
   /**
    * The available time slots where a new meeting can be created for the requested preferences.
    */
   @Json(name = "time_slots")
-  val timeSlots: List<TimeSlot>,
+  val timeSlots: List<TimeSlot>? = null,
 )
diff --git a/src/main/kotlin/com/nylas/resources/Calendars.kt b/src/main/kotlin/com/nylas/resources/Calendars.kt
index 14e991e4..8b8889f1 100644
--- a/src/main/kotlin/com/nylas/resources/Calendars.kt
+++ b/src/main/kotlin/com/nylas/resources/Calendars.kt
@@ -94,7 +94,9 @@ class Calendars(client: NylasClient) : Resource<Calendar>(client, Calendar::clas
       .adapter(GetAvailabilityRequest::class.java)
       .toJson(request)
 
-    return client.executePost(path, GetAvailabilityResponse::class.java, serializedRequestBody)
+    val responseType = Types.newParameterizedType(Response::class.java, GetAvailabilityResponse::class.java)
+
+    return client.executePost(path, responseType, serializedRequestBody)
   }
 
   /**