/**
     * Marks this value as being explicitly set with
     * the current value assigned to the convention,
     * unless it is already an explicit value.
     */
    public abstract S setToConventionIfUnset(S value);

    private static class NonFinalizedValue<S> extends ValueState<S> {
        private final PropertyHost host;
        private final Function<S, S> copier;
        private boolean explicitValue;

     * or if an explicit value has already been set, it has no effect.
     */
    protected SupportsConvention setToConventionIfUnset() {
        assertCanMutate();
        if (!isDefaultConvention()) {
            this.value = state.setToConventionIfUnset(value);
        }
        return this;
    }

    protected abstract S getDefaultValue();

     * or if an explicit value has already been set, it has no effect.
     */
    protected ConfigurableFileCollection setToConventionIfUnset() {
        assertMutable();
        value = valueState.setToConventionIfUnset(value);
        return this;
    }

    /**

        when:
        property.setToConventionIfUnset()

        then:
        assertValueIs(['4'])

        when:
        property.unset()
        property.setToConventionIfUnset()

        then:
        assertValueIs(['1'])
        property.explicit
    }

    def "property is empty when setToConventionIfUnset if convention not set yet"() {
        when:

        when:
        property.setToConventionIfUnset()

        then:
        assertValueIs(['k1': '4'])

        when:
        property.unset()
        property.setToConventionIfUnset()

        then:
        assertValueIs(['k0': '1'])
        property.explicit
    }

    def "property is empty when setToConventionIfUnset if convention not set yet"() {
        when:

        collection.from as List == ["src1"]

        when:
        collection.setToConventionIfUnset()

        then:
        collection.from as List == ["src1"]

        when:
        collection.unset()

        then:
        assert !collection.explicit

        when:
        collection.setToConventionIfUnset()

        then:
        assert collection.explicit

    protected Configurer getConfigurer(boolean ignoreAbsent) {
        return new Configurer(ignoreAbsent);
    }

    protected void withActualValue(Action<Configurer> action) {
        setToConventionIfUnset();
        action.execute(getConfigurer(true));
    }

    @Override
    protected boolean isDefaultConvention() {
        return isNoValueSupplier(getConventionSupplier());
    }

    }

    private Configurer getConfigurer(boolean ignoreAbsent) {
        return new Configurer(ignoreAbsent);
    }

    protected void withActualValue(Action<Configurer> action) {
        setToConventionIfUnset();
        action.execute(getConfigurer(true));
    }

    private boolean isNoValueSupplier(MapSupplier<K, V> valueSupplier) {
        return valueSupplier instanceof DefaultMapProperty.NoValueSupplier;