given:
        buildFile """

def prop = project.objects.listProperty(String)

task thing {
    inputs.property("prop", prop)
    prop.set(["value 1"])
    doLast {
        prop.set(["ignored"])
        println "prop = " + prop.get()
    }
}
"""

        when:
        fails("thing")

        then:

        given:
        buildFile << """

def prop = project.objects.mapProperty(String, String)
prop.set((Map)null)

task thing {
    inputs.property("prop", prop).optional(true)
    doLast {
        println "prop = " + prop.getOrNull()
    }
}
"""

        when:
        run("thing")

        then:
        output.contains("prop = null")
    }

            </activation>
            <properties>
                <groupId.prop>groupB</groupId.prop>
                <artifactId.prop>artifactB</artifactId.prop>
                <version.prop>1.4</version.prop>
            </properties>
        </profile>
    </profiles>
</project>
"""

        def transitiveModule = mavenHttpRepo.module("groupB", "artifactB", "1.4").publish()

        and:

            three.prop.disallowUnsafeRead()
            three.prop = two.prop.map { "[\$it]" }
            two.prop = one.prop.orElse("unknown")

            gradle.taskGraph.whenReady {
                println("three = " + three.prop.get())
                println("two = " + two.prop.get())
                println("one = " + one.prop.orNull)
                try {

        buildFile << """
ext.prop = "value 1"
repositories {
    assert prop == "value 1"
    prop = "value 2"
    maven {
        assert prop == "value 2"
        prop = "value 3"
        1.times {
            assert prop == "value 3"
            prop = "value 4"
            authentication {
                assert prop == "value 4"
                prop = "value 5"
            }
        }

                if (error != null) {
                    props.setProperty(key + ERROR_KEY_SUFFIX, error);
                } else {
                    props.remove(key + ERROR_KEY_SUFFIX);
                }

                getLogger().debug("Writing resolution-state to: " + touchfile);
                channel.truncate(0);

            thing.prop.disallowUnsafeRead()
            thing.prop.from(layout.buildDirectory)

            try {
                thing.prop.files
            } catch(IllegalStateException e) {
                println("get files failed with: " + e.message)
            }

            def elements = thing.prop.elements
            try {
                elements.get()

custom.prop = layout.buildDir.dir("dir3")
assert custom.prop.get().asFile == file("build/dir3")

custom.prop = file("dir4")
assert custom.prop.get().asFile == file("dir4")

custom.prop.set((Directory)null)
assert custom.prop.getOrNull() == null

custom.prop = file("foo")
custom.prop.set(null)
assert custom.prop.getOrNull() == null

custom.prop = file("foo")
custom.prop.set((File)null)

        given:
        buildFile << """

def prop = project.objects.fileProperty()

task thing {
    ${registrationMethod}(prop)
    prop.set(file("file-1"))
    def other = file("ignored")
    doLast {
        prop.set(other)
        println "prop = " + prop.get()
    }
}
"""
        file("file-1").createFile()

        when:

// are still needed internally to perform equality checks.
func escapeKeyProps(idents []string) []string {
	result := make([]string, len(idents))
	for i, prop := range idents {
		if escaped, ok := cel.Escape(prop); ok {
			result[i] = escaped
		} else {
			result[i] = prop
		}
	}
	return result
}

// unstructuredSetList represents an unstructured data instance of an OpenAPI array with x-kubernetes-list-type=set.