private static List<String> expectRecordStages(Callback<?> callback) {
        when(callback.chainStaging(any())).thenCallRealMethod();
        List<String> result = Collections.synchronizedList(new ArrayList<>());

        doAnswer(invocation -> {
            Stage stage = invocation.getArgument(0);
            if (stage != null)
                result.add(stage.description());
            return null;
        }).when(callback).recordStage(any());

        return result;
    }
Issues multiple rapid fencing requests for a handful of connectors, each of which takes a little while to complete.
This mimics what might happen when a few connectors are reconfigured in quick succession and each task for the
connector needs to hit the leader with a fencing request during its preflight check.
connect/runtime/src/test/java/org/apache/kafka/connect/runtime/distributed/DistributedHerderTest.java