User/lead initiated conversation using email returns 400 bad request #341

Version info

• intercom-php version: 4.2
• Intercom API version: 1.4
• PHP version: 7.3

Expected behavior

I am trying (as per the documentation here: https://developers.intercom.com/intercom-api-reference/v1.4/reference#user-or-contact-initiated-conversation) to initiate a conversation using an email address, like so:

    $response = $client->messages->create([
        'message_type' => 'inapp',
        'body' => 'Hello....',
        'from' => [
            'type' => 'contact',
            'email' => 'example_email_address@example.com',
        ]
    ]);

I am expecting this to create the conversation, as the documentation states:

"The sending user or lead is identified by their user_id, email or id values in the from field, along with a type field value of user orc contact."

Actual behavior

This returns a 400 bad request response, if 'email' is used in the from field.

Logs

PHP Fatal error: Uncaught Http\Client\Common\Exception\ClientErrorException: Bad Request in .../vendor/php-http/client-common/src/Plugin/ErrorPlugin.php:72