public static boolean isUpsertForNamedBlob(final Map<String, Object> args) throws RestServiceException {
    return getOptionalBooleanHeader(args, Headers.NAMED_UPSERT, false);
  }
Determine if {@link Headers#NAMED_UPSERT} is set in the request args.
@param args The request arguments.
@return {@code true} if {@link Headers#NAMED_UPSERT} is set to true else return false (default to false).
@throws RestServiceException if exception occurs during parsing the arg.
ambry-api/src/main/java/com/github/ambry/rest/RestUtils.java