private static void setFileAttribute(final HttpResponse response, final File backupFile) {
        FunctionUtils.doAndHandle(t -> {
            val path = backupFile.toPath();
            val etag = response.getFirstHeader("ETag").getValue();
            Files.setAttribute(path, "user:ETag", ByteBuffer.wrap(etag.getBytes(StandardCharsets.UTF_8)));
        });
    }
This is {@link MetadataQueryProtocolMetadataResolver}.

@author Misagh Moayyed
@since 5.2.0
support/cas-server-support-saml-idp-metadata/src/main/java/org/apereo/cas/support/saml/services/idp/metadata/cache/resolver/MetadataQueryProtocolMetadataResolver.java