public String getMsgType() {
        if (TStringUtils.isBlank(this.msgType)) {
            if (TStringUtils.isNotBlank(this.attribute)
                    && attribute.contains(TokenConstants.TOKEN_MSG_TYPE)) {
                parseSystemHeader();
            }
        }
        return this.msgType;
    }
init with indexId topic data attribute flag

@param indexId    index id
@param topic      topic name
@param data       message content
@param attribute  message attribute
@param flag       message flag
inlong-tubemq/tubemq-core/src/main/java/org/apache/inlong/tubemq/corebase/Message.java