@Override
    public int getOpCode() {
        return OP_CODE;
    }
Scheduler Get is an acknowledged message used to get the current Schedule Register state of an element (see Mesh Model Spec. v1.0.1 Section 5.1.4.2).
The response to the Scheduler Get message is a Scheduler Status message.

@param appKey {@link ApplicationKey} key for this message
@throws IllegalArgumentException if any illegal arguments are passed
mesh/src/main/java/no/nordicsemi/android/mesh/transport/SchedulerGet.java