abstract class LoggingListener implements BuildOperationListener, BuildService<BuildServiceParameters.None> {
                void started(BuildOperationDescriptor buildOperation, OperationStartEvent startEvent) { throw new RuntimeException() }
                void progress(OperationIdentifier operationIdentifier, OperationProgressEvent progressEvent) { throw new RuntimeException() }

        given:
        def startEvent1 = new ProgressStartEvent(new OperationIdentifier(-3L), new OperationIdentifier(-4L), tenAm, CATEGORY, "Execute :a", null, null, 0, true, new OperationIdentifier(-3L), BuildOperationCategory.TASK)
        def logEvent1 = event('a message', LogLevel.WARN, startEvent1.buildOperationId)
        def completeEvent1 = new ProgressCompleteEvent(startEvent1.progressOperationId, tenAm, "STATUS", false)

This new event breaks the convention of having a `StartEvent`-`FinishEvent` pair to express progress.
`TaskOutputEvent` is a simple `ProgressEvent`.

==== Changes to the task container behavior

The following deprecated methods on the task container now result in errors:

const fcpEvent=firstContentfulPaintEvents[fcpIndex];if(fcpEvent.start<startEvent.start){fcpIndex++;continue;}
loopStartIndex++;if(fcpIndex<2){continue;}