code: public AmqpTable addLongString(String key, String value) {
          this.add(key, value, AmqpType.LONGSTRING);
          return this;
      }
docs: Adds a long string entry to the AmqpTable.
  
  @param key    name of an entry
  @param value  long string value of an entry
  @return AmqpTable object that holds the table of entries