public abstract ExecutionTimeValue<T> withChangingContent();

        public abstract ExecutionTimeValue<T> withSideEffect(@Nullable SideEffect<? super T> sideEffect);

        public static <T> ExecutionTimeValue<T> missing() {
            return Cast.uncheckedCast(MISSING);
        }

        public static <T> ExecutionTimeValue<T> fixedValue(T value) {
            assert value != null;

                }
            }
        };
    }

    @Override
    public ExecutionTimeValue<? extends T> calculateExecutionTimeValue() {
        if (contentsAreBuiltByTask()) {
            return ExecutionTimeValue.changingValue(this);
        }
        return ExecutionTimeValue.fixedValue(get());
    }

    private boolean contentsAreBuiltByTask() {

            return provider.getProducer();
        }
    }

    @Override
    public ExecutionTimeValue<? extends T> calculateExecutionTimeValue() {
        try (EvaluationContext.ScopeContext context = openScope()) {
            ExecutionTimeValue<? extends T> value = provider.calculateExecutionTimeValue();
            if (value.isMissing()) {
                return value;
            }

            return provider.getProducer();
        }
    }

    @Override
    public ExecutionTimeValue<? extends OUT> calculateExecutionTimeValue() {
        try (EvaluationContext.ScopeContext context = openScope()) {
            ExecutionTimeValue<? extends IN> value = provider.calculateExecutionTimeValue();
            if (value.hasChangingContent()) {

            } else {
                return ValueProducer.unknown();
            }
        }

        @Override
        public ExecutionTimeValue<? extends T> calculateExecutionTimeValue() {
            ExecutionTimeValue<? extends T> value = super.calculateExecutionTimeValue();
            if (producer != null) {
                return value.withChangingContent();
            } else {

        @Override
        public ProviderInternal<T> withFinalValue(ValueConsumer consumer) {
            return this;
        }

        @Override
        public ExecutionTimeValue<? extends T> calculateExecutionTimeValue() {
            return ExecutionTimeValue.fixedValue(value);
        }

        @Override
        protected String toStringNoReentrance() {
            return String.format("fixed(%s, %s)", getType(), value);

        return decodeValue().toProvider()
    }

    suspend fun ReadContext.decodeValue(): ValueSupplier.ExecutionTimeValue<*> =
        when (readByte()) {
            1.toByte() -> ValueSupplier.ExecutionTimeValue.missing<Any>()
            2.toByte() -> ValueSupplier.ExecutionTimeValue.ofNullable(read()) // nullable because serialization may replace value with null, e.g. when using provider of Task
            3.toByte() -> {

    public Optional<FileCollectionExecutionTimeValue> calculateExecutionTimeValue() {
        FileCollectionExecutionTimeValue executionTimeValue = displayName.equals(DEFAULT_COLLECTION_DISPLAY_NAME)
            ? EmptyExecutionTimeValue.INSTANCE
            : new EmptyExecutionTimeValue(displayName);

        return Optional.of(executionTimeValue);
    }

    private static class EmptyExecutionTimeValue implements FileCollectionExecutionTimeValue {

        }
        return ValueSupplier.Value.ofNullable(result)
    }

    override fun calculateExecutionTimeValue(): ValueSupplier.ExecutionTimeValue<out BuildWorkResult> =
        ValueSupplier.ExecutionTimeValue.changingValue(this)

        super(value);
    }

    @Override
    protected String toStringNoReentrance() {
        return "changing(?)";
    }

    @Override
    public ExecutionTimeValue<? extends T> calculateExecutionTimeValue() {
        return ExecutionTimeValue.changingValue(this);
    }