code: public void setStructuredAppendMessageId(String messageId) {
          if (messageId != null && !messageId.matches("^[\\x21-\\x7F]+$")) {
              throw new IllegalArgumentException("Invalid Aztec Code structured append message ID: " + messageId);
          }
          this.structuredAppendMessageId = messageId;
      }
docs: If this Aztec Code symbol is part of a series of Aztec Code symbols appended in a structured format,
  this method sets the unique message ID for the series. Values may not contain spaces and must contain
  only printable ASCII characters. Message IDs are optional.
  
  @param messageId the unique message ID for the series that this symbol is part of