sender.java

final PushSender sender =
    DefaultPushSender.withRootServerURL("{{ contextPath }}")
        .pushApplicationId("{{ app.pushApplicationID }}")
        .masterSecret("{{ app.masterSecret }}")
    .build();

final UnifiedMessage unifiedMessage = UnifiedMessage.
    withMessage()
        .alert("Hello from Java Sender API!")
    .build();

 
sender.send(unifiedMessage, () -> {
    //do cool stuff
});