SequenceFlow drag event

I’m trying to catch event changes of a bpmn:SequenceFlow of type drag. So I’m searching for an event that lists what was the previous sibling element connected to the sequenceFlow before its change, example:
The hovered sequenceFlow below is connected as target to a gateway
Screenshot from 2020-02-28 12-40-12
then we drag the same connection to change its target to a task instead of a gateway
Screenshot from 2020-02-28 12-40-27
Then what kind of event to listen for to catch that the sequenceFlow was connected to the gateway?
Any hints please

connection.reconnect is the event you’re looking for.