Setting FCM credentials

FCM XMPP API provider will not work properly without API key and project id as this values are required for authorization by FCM. You need to get information from FCM account.

When you have this data, you need to pass sender id as sender-id property and server key as server-key property.

Example. 

push () {
    'fcm-xmpp-api' () {
        'sender-id' = 'your-sender-id'
        'server-key' = 'your-server-key'
    }
}