}
        }
    }

    override fun flagRead(flag: FeatureFlag) {
        flag.systemPropertyName?.let { propertyName ->
            sink().systemPropertyRead(propertyName, System.getProperty(propertyName))
        }
    }

    fun append(fingerprint: ProjectSpecificFingerprint) {
        // TODO - should add to report as an input

    public abstract fun getTypeAliasByClassId(classId: ClassId): KaTypeAliasSymbol?

    public abstract fun getTopLevelCallableSymbols(packageFqName: FqName, name: Name): Sequence<KaCallableSymbol>

    @Suppress("PropertyName")
    public abstract val ROOT_PACKAGE_SYMBOL: KaPackageSymbol
}

public typealias KtSymbolProvider = KaSymbolProvider

public interface KaSymbolProviderMixIn : KaSessionMixIn {

    }

    @Override
    public Object property(String propertyName) throws MissingPropertyException {
        return dynamicLookupRoutine.property(extensibleDynamicObject, propertyName);
    }

    @Override
    public Object findProperty(String propertyName) {
        return dynamicLookupRoutine.findProperty(extensibleDynamicObject, propertyName);
    }

    @Override

    }

    private static class EmptyGradleProperties implements GradleProperties {
        @Nullable
        @Override
        public Object find(String propertyName) {
            return null;
        }

        @Override
        public Map<String, Object> mergeProperties(Map<String, Object> properties) {
            return properties;
        }

        @Override

        given:
        def problem = problemReporter.create {
            it.id("id", "label", GradleCoreProblemGroup.validation())
                .additionalData(TypeValidationDataSpec.class) {
                    it.propertyName("property")
                    it.typeName("type")
                    it.parentPropertyName("parent")
                    it.pluginId("id")
                }
        }

        when:

                'Mark property \'destFile\' as optional',
            ]
            additionalData.asMap == [
                'typeName' : 'CustomTask',
                'propertyName' : 'destFile',
            ]
        }
        verifyAll(receivedProblem(1)) {
            fqid == 'validation:property-validation:value-not-set'

        KaFirJavaSyntheticPropertySymbolPointer(
            ownerPointer = analysisSession.createOwnerPointer(this),
            propertyName = name,
            isSynthetic = firSymbol is SyntheticSymbol,
        )
    }

    override fun equals(other: Any?): Boolean = symbolEquals(other)
    override fun hashCode(): Int = symbolHashCode()

            ].collect { it.toString() }
            additionalData.asMap == [
                'typeName': 'org.gradle.api.DefaultTask',
                'propertyName': 'input',
            ]
        }

        where:
        method | path             | fileType
        "file" | "input-dir"      | "file"
        "dir"  | "input-file.txt" | "directory"
    }

        override val ignoredFileSystemCheckInputs: String?
            get() = startParameter.ignoredFileSystemCheckInputs

        override fun gradleProperty(propertyName: String): String? =
            gradleProperties.find(propertyName)?.uncheckedCast()

        override fun hashCodeOf(file: File) =
            hashCodeAndTypeOf(file).first

     *
     * </ol>
     *
     * @param propertyName The name of the property.
     * @return The value of the property, possibly null.
     * @throws MissingPropertyException When the given property is unknown.
     */
    @Nullable
    Object property(String propertyName) throws MissingPropertyException;

    /**