Changing MUC nickname to one that's already used by your other resource
Description
When you're using more than one device (resources), and join the same MUC room, Openfire allows you to re-use the same nickname. This allows you to act as one occupant, instead of having a 'nickname-per-device'.
Currently, a conflict error is returned when you first join a MUC with two different nicknames, and then try to rename yourself on one device to use the same nickname as the other device.
When you're using more than one device (resources), and join the same MUC room, Openfire allows you to re-use the same nickname. This allows you to act as one occupant, instead of having a 'nickname-per-device'.
Currently, a conflict error is returned when you first join a MUC with two different nicknames, and then try to rename yourself on one device to use the same nickname as the other device.
This problem was identified (and a fix provided) by MightyMop in https://github.com/mightymop/Openfire/commit/47b64c4c9d45e78630d8bd05bd2c7afda9890b5d