function convertComposerOptions(options) {
    const locale = isString(options.locale) ? options.locale : 'en-US';
    const fallbackLocale = isString(options.fallbackLocale) ||
        isArray(options.fallbackLocale) ||
        isPlainObject(options.fallbackLocale) ||
        options.fallbackLocale === false
        ? options.fallbackLocale
        : locale;
    const missing = isFunction(options.missing) ? options.missing : undefined;
    const missingWarn = isBoolean(options.silentTranslationWarn) ||
        isRegExp(options.silentTranslationWarn)
        ? !options.silentTranslationWarn
        : true;
    const fallbackWarn = isBoolean(options.silentFallbackWarn) ||
        isRegExp(options.silentFallbackWarn)
        ? !options.silentFallbackWarn
        : true;
    const fallbackRoot = isBoolean(options.fallbackRoot)
        ? options.fallbackRoot
        : true;
    const fallbackFormat = !!options.formatFallbackMessages;
    const modifiers = isPlainObject(options.modifiers) ? options.modifiers : {};
    const pluralizationRules = options.pluralizationRules;
    const postTranslation = isFunction(options.postTranslation)
        ? options.postTranslation
        : undefined;
    const warnHtmlMessage = isString(options.warnHtmlInMessage)
        ? options.warnHtmlInMessage !== 'off'
        : true;
    const escapeParameter = !!options.escapeParameterHtml;
    const inheritLocale = isBoolean(options.sync) ? options.sync : true;
    if ((process.env.NODE_ENV !== 'production') && options.formatter) {
        warn(getWarnMessage(8 /* NOT_SUPPORTED_FORMATTER */));
    }
    if ((process.env.NODE_ENV !== 'production') && options.preserveDirectiveContent) {
        warn(getWarnMessage(9 /* NOT_SUPPORTED_PRESERVE_DIRECTIVE */));
    }
    let messages = options.messages;
    if (isPlainObject(options.sharedMessages)) {
        const sharedMessages = options.sharedMessages;
        const locales = Object.keys(sharedMessages);
        messages = locales.reduce((messages, locale) => {
            const message = messages[locale] || (messages[locale] = {});
            assign(message, sharedMessages[locale]);
            return messages;
        }, (messages || {}));
    }
    const { __i18n, __root, __injectWithOption } = options;
    const datetimeFormats = options.datetimeFormats;
    const numberFormats = options.numberFormats;
    const flatJson = options.flatJson;
    return {
        locale,
        fallbackLocale,
        messages,
        flatJson,
        datetimeFormats,
        numberFormats,
        missing,
        missingWarn,
        fallbackWarn,
        fallbackRoot,
        fallbackFormat,
        modifiers,
        pluralRules: pluralizationRules,
        postTranslation,
        warnHtmlMessage,
        escapeParameter,
        inheritLocale,
        __i18n,
        __root,
        __injectWithOption
    };
}
Convert to I18n Composer Options from VueI18n Options

@internal