public WorkflowTask getTaskByRefName(String taskReferenceName) {
        return collectTasks().stream()
                .filter(
                        workflowTask ->
                                workflowTask.getTaskReferenceName().equals(taskReferenceName))
                .findFirst()
                .orElse(null);
    }
@param variables the set of global workflow variables to set
common/src/main/java/com/netflix/conductor/common/metadata/workflow/WorkflowDef.java