/**
     * A key corresponding to the spec that is an immutable snapshot of the spec properties
     * suitable for usage in collections.
     */
    interface Key {}

    Key toKey();

    /**
     * A spec is considered configured when at least {@link #getLanguageVersion() language version} is set.
     * <p>
     * A spec that is not configured always directly matches the toolchain of the current JVM.

    public DefaultToolchainSpec() {
        getVendor().convention(getConventionVendor());
        getImplementation().convention(getConventionImplementation());
    }
    @Override
    public JavaToolchainSpecInternal.Key toKey() {
        return new Key(getLanguageVersion().getOrNull(), getVendor().getOrNull(), getImplementation().getOrNull());
    }

    @Override
    public boolean isConfigured() {

        return objectFactory.newInstance(SpecificInstallationToolchainSpec.class, JavaExecutableUtils.resolveJavaHomeOfExecutable(executable));
    }

    @Override
    public Key toKey() {
        return new Key(javaHome);
    }

    @Override
    public boolean isConfigured() {
        return true;
    }

    @Override
    public boolean isValid() {
        return true;
    }

        // We can't use the key of the fallback toolchain spec, because it is a spec that can match configured requests as well
        JavaToolchainSpecInternal.Key actualKey = useFallback ? FALLBACK_TOOLCHAIN_KEY : requestedSpec.toKey();

        Object resolutionResult = matchingToolchains.computeIfAbsent(actualKey, key -> {
            try {
                return query(actualSpec, useFallback);
            } catch (Exception e) {