Add created_at field to create conversation request body for v2.11+ (#211)

Author: steve-henry

descriptions/0/api.intercom.io.yaml

@@ -15539,6 +15539,11 @@ components:
           type: string
           description: The content of the message. HTML is not supported.
           example: Hello
+        created_at:
+          type: integer
+          format: date-time
+          description: The time the conversation was created as a UTC Unix timestamp. If not provided, the current time will be used. This field is only recommneded for migrating past conversations from another source into Intercom.
+          example: 1671028894
       required:
       - from
       - body

descriptions/2.11/api.intercom.io.yaml

@@ -14381,6 +14381,11 @@ components:
           type: string
           description: The content of the message. HTML is not supported.
           example: Hello
+        created_at:
+          type: integer
+          format: date-time
+          description: The time the conversation was created as a UTC Unix timestamp. If not provided, the current time will be used. This field is only recommneded for migrating past conversations from another source into Intercom.
+          example: 1671028894
       required:
       - from
       - body

descriptions/2.12/api.intercom.io.yaml

@@ -14681,6 +14681,11 @@ components:
           type: string
           description: The content of the message. HTML is not supported.
           example: Hello
+        created_at:
+          type: integer
+          format: date-time
+          description: The time the conversation was created as a UTC Unix timestamp. If not provided, the current time will be used. This field is only recommneded for migrating past conversations from another source into Intercom.
+          example: 1671028894
       required:
       - from
       - body