E/~!a: Unable to show GCM notification
   Sdk Version: 5.5.1
   Google Play Services Version: 11910000
   java.lang.IllegalStateException: Missing required properties: id alert
       at com.salesforce.marketingcloud.notifications.$$AutoValue_NotificationMessage$a.c(Unknown Source)
       at com.salesforce.marketingcloud.notifications.NotificationMessage$a.d(Unknown Source)
       at com.salesforce.marketingcloud.notifications.NotificationMessage.a(Unknown Source)
       at com.salesforce.marketingcloud.messages.push.a.c(Unknown Source)
       at com.salesforce.marketingcloud.messages.push.a.a(Unknown Source)
       at com.salesforce.marketingcloud.messages.push.a$a.onReceive(Unknown Source)
       at android.support.v4.content.LocalBroadcastManager.executePendingBroadcasts(LocalBroadcastManager.java:311)
       at android.support.v4.content.LocalBroadcastManager.access$000(LocalBroadcastManager.java:47)
       at android.support.v4.content.LocalBroadcastManager$1.handleMessage(LocalBroadcastManager.java:120)
       at android.os.Handler.dispatchMessage(Handler.java)
       at android.os.Looper.loop(Looper.java)
       at android.app.ActivityThread.main(ActivityThread.java)
       at java.lang.reflect.Method.invoke(Native Method)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java)