This parameter identifies a group of messages that can be collapsed.
When a notification or message is sent and this is set to true, an inactive client app is awoken.
This parameter specifies the key-value pairs of the message's payload.
When this parameter is set to true, it indicates that the message should not be sent until the device becomes active.
This parameter, when set to true, allows developers to test a request without actually sending a message.
This parameter specifies the key-value pairs of the notification payload.
Sets the priority of the message. Valid values are "normal" and "high".
This parameter specifies the package name of the application where the registration tokens must match in order to receive the message.
This parameter specifies how long (in seconds) the message should be kept in GCM storage if the device is offline.