title: java slack bot integration join channel tag
body: <p>I have a java app that acts like slack bot and sends text messages to slack channel. But, if I send 'Please join #mysuperchannel', the #mysuperchannel is not highlighted as a link which I can join that channel in one click. It's just a text. What should  I use to get this #mysuperchannel word be highlighted and clickable in slack chat window? Sth like a tag or mark or anything else to let it know I want to get this word like a reference to the channel it represents.   Thanks</p>