The event is triggered after the object is transferred, so the objects' .player property will indicate who now owns it.
Both players will receive the event (not that it matters much to your script).
If the object was in a group, it will be removed from the group. On Warzone 3.2 or above, that will trigger eventGroupLoss().
Example
Handle all possible scenarios
eventObjectTransfer(gameObject, from) {
if (gameObject.player == me) { // I gained a new object
if (allianceExistsBetween(me,from)) { // a gift from an ally
// do stuff
} else { // probably Nexus Link assimilated it from an enemy
// do stuff
}
} else { // I lost an object
if (allianceExistsBetween(gameObject.player,from)) { // I gave a droid to my ally
// do stuff
} else { // looks like an enemy Nexus Link assimilated one of my droids :(
// do stuff
}
}
}