public Builder setNumber(int number) {
            mNumber = number;
            return this;
        }
Set the large number at the right-hand side of the notification.  This is
equivalent to setContentInfo, although it might show the number in a different
font size for readability.
android/android_framework/base/src/main/java/github/tornaco/android/thanos/core/compat/NotificationCompat.java