static realObj_(obj) {
    if (obj['sample']) {
      return obj['sample'];
    } else {
      return obj;
    }
  }
Gets the backing object of the given field.  When using
jasmine.objectContaining, the resulting object doesn't have the fields we
want, so we return the backing object.

@template T
@param {T} obj
@return {T}
@private