if (value.isMissing()) {
                return value.asType();
            }
            collector.add(key, value.getWithoutSideEffect(), dest);
            return Value.present().withSideEffect(SideEffect.fixedFrom(value));
        }

        @Override
        public Value<Void> collectKeys(ValueConsumer consumer, ValueCollector<K> collector, ImmutableCollection.Builder<K> dest) {

            result.add(value.getWithoutSideEffect());
        }

        Value<List<R>> finalValue = Value.ofNullable(result.build());
        for (Value<? extends R> value : values) {
            finalValue = finalValue.withSideEffect(SideEffect.fixedFrom(value));
        }

        return finalValue;
    }

    @Nullable
    @Override
    public Class<List<R>> getType() {
        return Cast.uncheckedCast(List.class);
    }

        // as the transformed provider can have side effects hidden under other wrapping providers.
        return Providers.internal(transformedProvider).withSideEffect(SideEffect.fixedFrom(value));
    }

    private ProviderInternal<? extends S> backingProvider(EvaluationContext.ScopeContext context, ValueConsumer consumer) {

            if (value.isMissing()) {
                return value.asType();
            }

            collector.add(value.getWithoutSideEffect(), collection);
            return Value.present().withSideEffect(SideEffect.fixedFrom(value));
        }

        @Override
        public boolean isProvidedBy(Provider<?> provider) {
            return Objects.equal(provider, this.provider);
        }

        def expectedUnpackedValue = ["some key": "some value", "other key": "other value"]

        when:
        property.put("some key", Providers.of("some value").withSideEffect(sideEffect1))
        property.put("other key", Providers.of("other value").withSideEffect(sideEffect2))

        def value = property.calculateValue(ValueSupplier.ValueConsumer.IgnoreUnsafeRead)

        } else {
            ProviderInternal<T> provider = of(value.getWithoutSideEffect());
            ValueSupplier.SideEffect<?> sideEffect = value.getSideEffect();
            return sideEffect == null ? provider : provider.withSideEffect(Cast.uncheckedCast(sideEffect));
        }
    }

    public static <T> ProviderInternal<T> notDefined() {
        return Cast.uncheckedCast(NULL_PROVIDER);
    }

        def expectedUnpackedValue = ["some value", "simple value", "other value"]

        when:
        property.add(Providers.of("some value").withSideEffect(sideEffect1))
        property.add(Providers.of("simple value"))
        property.add(Providers.of("other value").withSideEffect(sideEffect2))

        def value = property.calculateValue(ValueSupplier.ValueConsumer.IgnoreUnsafeRead)

                // nullable because serialization may replace value with null, e.g. when using provider of Task
                ValueSupplier.ExecutionTimeValue.ofNullable(value).withSideEffect(sideEffect)
            }

            4.toByte() -> ValueSupplier.ExecutionTimeValue.changingValue<Any>(providerWithChangingValueCodec.run { decode() }!!.uncheckedCast())

     * This new "fixed" side effect will be executed when the resulting provider produces its values.
     */
    default ProviderInternal<T> withSideEffect(@Nullable SideEffect<? super T> sideEffect) {
        return WithSideEffectProvider.of(this, sideEffect);
    }

        given:
        def property = providerWithNoValue()

        when:
        def sideEffect = Mock(ValueSupplier.SideEffect)
        def providerWithSideEffect = Providers.of(someValue()).withSideEffect(sideEffect)
        // `PropertyInternal` does not directly provide these setters,
        // but all user-facing interfaces and their implementations do.
        property."$setter"(providerWithSideEffect)