Can't edit a customer's extra field

[joaquin-alonso]

When creating a customer via API by doing a POST to /customers, I can easily set custom data with the extra field. E.g.:

{
    "name": "Testing McTester",
    "email": "[email protected]",
    "send_email_invite": true,
    "password": "123",
    "extra": {
        "color": "red"
    }
}

However, I'm not able to edit this info with a PUT to /customers/:customerId. I tried using this body, but the data in extra is not being edited.

{
    "billing_name": "Johnny McJohnny",
    "extra": {
        "color": "green"
    }
}