Missing: conversation 'customer_first_reply'

Hi,

The 'Conversation' class is missing the 'customer_first_reply' property.

Is there a way to get the property value?

"customer_first_reply": {
        "created_at": 1572027728,
        "type": "conversation",
        "url": "xxx/2502959-teste"
    },

## Version info
  - intercom-java version:2.8.0
  - Java version:8
