function _checkNotImplementedPolicy(policyString) {
    // bucket names and key names cannot include "", so including those
    // isolates not implemented keys
    return policyString.includes('"Service"')
        || policyString.includes('"Federated"');
}
_checkNotImplementedPolicy - some bucket policy features have not been
implemented and should return NotImplemented error
@param {string} policyString - string bucket policy
@return {boolean} - returns true if policy contains not implemented elements