@VisibleForTesting
    void validateTasks(List<TaskModel> tasks) {
        Preconditions.checkNotNull(tasks, "Tasks object cannot be null");
        Preconditions.checkArgument(!tasks.isEmpty(), "Tasks object cannot be empty");
        tasks.forEach(
                task -> {
                    Preconditions.checkNotNull(task, "task object cannot be null");
                    Preconditions.checkNotNull(task.getTaskId(), "Task id cannot be null");
                    Preconditions.checkNotNull(
                            task.getWorkflowInstanceId(), "Workflow instance id cannot be null");
                    Preconditions.checkNotNull(
                            task.getReferenceTaskName(), "Task reference name cannot be null");
                });

        String workflowId = tasks.get(0).getWorkflowInstanceId();
        Optional<TaskModel> optionalTask =
                tasks.stream()
                        .filter(task -> !workflowId.equals(task.getWorkflowInstanceId()))
                        .findAny();
        if (optionalTask.isPresent()) {
            throw new NonTransientException(
                    "Tasks of multiple workflows cannot be created/updated simultaneously");
        }
    }
This is a dummy implementation and this feature is not implemented for Cassandra backed
Conductor
cassandra-persistence/src/main/java/com/netflix/conductor/cassandra/dao/CassandraExecutionDAO.java