@Override
    public int getOpCode() {
        return OP_CODE;
    }
Constructs ConfigModelAppUnbind message.

@param elementAddress  Address of the element to which the model belongs to
@param modelIdentifier Model from which the key must be unbound from
@param appKeyIndex     Global app key index of the key to be unbound
@throws IllegalArgumentException if any illegal arguments are passed
mesh/src/main/java/no/nordicsemi/android/mesh/transport/ConfigModelAppUnbind.java