def registry = createRegistry([jdk8])
        def installations = registry.listInstallations()
        def installations2 = registry.listInstallations()

        then:
        installations.is(installations2)
    }

    def "normalize installations to account for macOS folder layout"() {
        given:
        def jdkHome = temporaryFolder.createDir("jdk")
        def macOsJdkHome = jdkHome.createDir("Contents/Home")

                abstract JavaInstallationRegistry getRegistry()

                void apply(Project project) {
                    project.tasks.register("show") {
                        def installations = registry.listInstallations()
                        assert installations.size() == 1
                        assert installations[0].location == org.gradle.internal.jvm.Jvm.current().javaHome
                    }
                }
            }

    protected Set<InstallationLocation> listInstallations() {
        return installations.get();
    }

    @Override
    public List<JvmToolchainMetadata> toolchains() {
        ProgressLogger progressLogger = progressLoggerFactory.newOperation(JavaInstallationRegistry.class).start("Discovering toolchains", "Discovering toolchains");
        List<JvmToolchainMetadata> result = listInstallations()
            .parallelStream()