Repeated warning message - WARN: Invalid message state transition from SCHEDULED_TO_SEND suggested: SCHEDULED_TO_SEND

[isuruirj]

Description:
I have created a sample JMS application to try out topics in WSO2 Message Broker (MB) with Subscribing and Publishing.

One thing I have noticed is that my MB server now has this repeated logging messages in wso2carbon.log file. It says some warning that is mentioned on this page[1].

[2019-02-14 10:04:42,693] WARN {org.wso2.andes.kernel.DeliverableAndesMetadata} - Invalid message state transition from SCHEDULED_TO_SEND suggested: SCHEDULED_TO_SEND Message ID: 67408463079145472 slot = AMQP_Topic_news.sport_NODE:isurus-MacBook-Pro.local/127.0.0.1|0-67408463079145472 Message Status History >> [READ, BUFFERED, SCHEDULED_TO_SEND]

Affected Product Version:
wso2ei-6.1.1

Steps to reproduce:
Please find the sample application from here[2].

[1] - https://docs.wso2.com/display/MB320/Troubleshooting+WSO2+Message+Broker
[2] - https://github.com/isuruirj/JMS-Client

[abeykoon]

This issue is reproducible after the fix with following scenario

1. Add two subscribers for some topic.
2. send a message to that topic

In that case, you will see the following log.

[2019-03-18 13:49:14,475] [EI-Broker]  WARN {org.wso2.andes.kernel.DeliverableAndesMetadata} -  Invalid message state transition from SCHEDULED_TO_SEND suggested: SCHEDULED_TO_SEND Message ID: 68136770741469186 slot = AMQP_Topic_mytopic1_NODE:Hasithas-MacBook-Pro.local/127.0.0.1|0-68136770742255618 Message Status History >> [READ, BUFFERED, SCHEDULED_TO_SEND]