private Source userToolchainsSource;

    @Override
    public Source getGlobalToolchainsSource() {
        return globalToolchainsSource;
    }

    @Override
    public ToolchainsBuildingRequest setGlobalToolchainsSource(Source globalToolchainsSource) {
        this.globalToolchainsSource = globalToolchainsSource;
        return this;
    }

    @Override
    public Source getUserToolchainsSource() {

     *
     * @param globalToolchainsSource The global toolchains source, may be {@code null} to disable global toolchains.
     * @return This request, never {@code null}.
     */
    ToolchainsBuildingRequest setGlobalToolchainsSource(Source globalToolchainsSource);

    /**
     * Gets the user toolchains source.
     *
     * @return The user toolchains source or {@code null} if none.
     */
    Source getUserToolchainsSource();

        String xml = new DefaultToolchainsXmlFactory().toXmlString(persistedToolchains.getDelegate());
        ToolchainsBuildingRequest request = new DefaultToolchainsBuildingRequest();
        request.setGlobalToolchainsSource(new StringSource(xml));

        ToolchainsBuildingResult result = toolchainBuilder.build(request);
        assertNotNull(result.getEffectiveToolchains());

        DefaultToolchainsBuildingRequest toolchainsRequest = new DefaultToolchainsBuildingRequest();
        if (installationToolchainsFile != null && installationToolchainsFile.isFile()) {
            toolchainsRequest.setGlobalToolchainsSource(new FileSource(installationToolchainsFile));
        }
        if (userToolchainsFile != null && userToolchainsFile.isFile()) {
            toolchainsRequest.setUserToolchainsSource(new FileSource(userToolchainsFile));