code: public static void addAsyncProperty(String key, String value, TransactionLogger transactionLogger) {
  
      FlowContextFactory.deserializeNativeFlowContext(transactionLogger.getFlowContextAsync(transactionLogger));
      transactionLogger.properties.put(key, value);
  
    }
docs: Add property to 'properties' map on transaction
  @param key - of property
  @param value - of property
  @param transactionLogger