/** * Defines the system reaction. The system will react as specified to the * current step's events, when you call * {@link ModelRunner#reactTo(Object)}. * * @param systemReaction * the specified system reaction * @return the created system part of this step */ public StepSystemPart<T> system(Consumer<T> systemReaction) { Objects.requireNonNull(systemReaction); return new StepSystemPart<>(stepPart, systemReaction); }