_loadAllMissing(newLocale, oldLocale) {
    const oldLocaleNamespaces = this.__storage[oldLocale] || {};
    const newLocaleNamespaces = this.__storage[newLocale] || {};
    Object.keys(oldLocaleNamespaces).forEach(namespace => {
      const newNamespaceData = newLocaleNamespaces[namespace];
      if (!newNamespaceData) {
        this.loadNamespace(namespace, {
          locale: newLocale,
        });
      }
    });
  }
@param {string} newLocale
@param {string} oldLocale
@protected