snaker-core/src/main/java/org/snaker/engine/core/TaskService.java
private String[] getTaskActors(TaskModel model, Execution execution) {
		Object assigneeObject = null;
        AssignmentHandler handler = model.getAssignmentHandlerObject();
		if(StringHelper.isNotEmpty(model.getAssignee())) {
			assigneeObject = execution.getArgs().get(model.getAssignee());
		} else if(handler != null) {
            if(handler instanceof Assignment) {
                assigneeObject = ((Assignment)handler).assign(model, execution);
            } else {
                assigneeObject = handler.assign(execution);
            }
		}
		return getTaskActors(assigneeObject == null ? model.getAssignee() : assigneeObject);
	}
private String[] getTaskActors(TaskModel model, Execution execution) {
		Object assigneeObject = null;
        AssignmentHandler handler = model.getAssignmentHandlerObject();
		if(StringHelper.isNotEmpty(model.getAssignee())) {
			assigneeObject = execution.getArgs().get(model.getAssignee());
		} else if(handler != null) {
            if(handler instanceof Assignment) {
                assigneeObject = ((Assignment)handler).assign(model, execution);
            } else {
                assigneeObject = handler.assign(execution);
            }
		}
		return getTaskActors(assigneeObject == null ? model.getAssignee() : assigneeObject);
	}
根据Task模型的assignee、assignmentHandler属性以及运行时数据，确定参与者
@param model 模型
@param execution 执行对象
@return 参与者数组