public String ownerUrl(String connector) {
        if (rejoinNeededOrPending() || !isLeader())
            return null;
        return leaderState().ownerUrl(connector);
    }
Return id that corresponds to the group generation that was active when the last join was successful

@return the generation ID of the last group that was joined successfully by this member or -1 if no generation
was stable at that point
connect/runtime/src/main/java/org/apache/kafka/connect/runtime/distributed/WorkerCoordinator.java