public static Map<String, String> requestInfoForKerberosDescriptor(KerberosDescriptor descriptor) {
    return ImmutableMap.of(Request.REQUEST_INFO_BODY_PROPERTY, ArtifactResourceProvider.toArtifactDataJson(descriptor.toMap()));
  }
@return {@code Optional} with the cluster's kerberos descriptor artifact if it exists, otherwise empty {@code Optional}
ambari-server/src/main/java/org/apache/ambari/server/topology/addservice/ResourceProviderAdapter.java