this.installationToolchainsSource = installationToolchainsSource;
            return this;
        }

        public ToolchainsBuilderRequestBuilder userToolchainsSource(Source userToolchainsSource) {
            this.userToolchainsSource = userToolchainsSource;
            return this;
        }

        public ToolchainsBuilderRequest build() {

        return this;
    }

    @Override
    public Source getUserToolchainsSource() {
        return userToolchainsSource;
    }

    @Override
    public ToolchainsBuildingRequest setUserToolchainsSource(Source userToolchainsSource) {
        this.userToolchainsSource = userToolchainsSource;
        return this;
    }

     * take precedence.
     *
     * @param userToolchainsSource The user toolchains source, may be {@code null} to disable user toolchains.
     * @return This request, never {@code null}.
     */
    ToolchainsBuildingRequest setUserToolchainsSource(Source userToolchainsSource);

    default ToolchainsBuilderResult build(
            @Nonnull Session session,
            @Nonnull Source installationToolchainsFile,
            @Nonnull Source userToolchainsSource) {
        return build(ToolchainsBuilderRequest.build(session, installationToolchainsFile, userToolchainsSource));
    }

                                ? Sources.fromPath(installationToolchainsFile)
                                : null)
                .userToolchainsSource(
                        userToolchainsFile != null && Files.isRegularFile(userToolchainsFile)
                                ? Sources.fromPath(userToolchainsFile)
                                : null)