@goeland86 here is my code: https://github.com/Schoaf/mattermost-jira-info-allChannels
As you can see there are still problems I need to solve maybe you can help me with that: https://github.com/Schoaf/mattermost-jira-info-allChannels/issues
One problem: If I change the icon of the return message only I (admin) can see them. For all others there is a broken icon image.
Another problem. Only I (admin) can use it in private messages. Does not matter if they are addressing me or comming from me. But if other users try to use it in their private message conversations, it doesn't work. Strange.. But I'll figure it out!