public void assignActiveToConsumer(final TaskId task, final String consumer) {
        if (!assignedActiveTasks.taskIds().contains(task)) {
            throw new IllegalStateException("added not assign active task " + task + " to this client state.");
        }
        assignedActiveTasks.consumerToTaskIds()
                           .computeIfAbsent(consumer, k -> new HashSet<>()).add(task);
    }
@Test
    public void shouldThrowIllegalStateExceptionIfAssignedTasksForConsumerToNonClientAssignActive() {
        assertThrows(IllegalStateException.class, () -> client.assignActiveToConsumer(TASK_0_0, "c1"));
    }