private static String getRawKerberosDescriptorFromRequest(Request request) {
    Map<String, String> requestInfoProperties = request.getRequestInfoProperties();
    if (requestInfoProperties != null) {
      String descriptorText = requestInfoProperties.get(Request.REQUEST_INFO_BODY_PROPERTY);
      if (!Strings.isNullOrEmpty(descriptorText)) {
        return descriptorText;
      }
    }

    String msg = "No Kerberos descriptor found in the request body";
    LOGGER.error(msg);
    throw new IllegalArgumentException(msg);
  }
@throws IllegalArgumentException if descriptor text is not found or is empty
ambari-server/src/main/java/org/apache/ambari/server/controller/internal/KerberosDescriptorResourceProvider.java