@Override
    public TaskProgress getTaskProgress(final TaskContext taskContext) {
        if (taskContext instanceof final TaskContextImpl taskContextImpl) {
            return buildTaskProgress(System.currentTimeMillis(), taskContextImpl);
        }
        return null;
    }
Tells tasks to terminate and waits for all tasks to terminate before
cleaning up the executors.
stroom-task/stroom-task-impl/src/main/java/stroom/task/impl/TaskManagerImpl.java