Can't see the workflow trace

Discussed in https://github.com/traceloop/openllmetry/discussions/1804

^{Originally posted by eric-easyhealth August 6, 2024}
I'm using Haystack2 with latest trackloop 0.26.4, followed the offical guidance to init the traceloop by following code:

Traceloop.init(app_name="app_name", api_key="apikey")

it works perfect and shown me the openai track as following, but how can i enable the workflow track like what is suggested in the quick start document?
PS: i'm using a pipeline in a python class, dummy code as below:

from haystack import Pipeline
from haystack.components.generators.chat import OpenAIChatGenerator

class ChatPipelineViaRAG:
    def __init__(self, api_key:str = '')
        self.retrieve_pipeline = Pipeline()
        self.generator = OpenAIChatGenerator()
        ......
    
    def run(self, messages: List[ChatMessage]) -> dict[str, Any]:
        retrieved_documents = self.retrieve_pipeline.run(parameters...)
        self.messages = process_documents(messages, retrieved_documents)
        return self.generator.run(self.messages)
        

Start with the Traceloop.init call and the quick start guidance referenced in the issue, then examine how the Haystack Pipeline and OpenAIChatGenerator are used in the example. Determine whether the shown class-based pipeline produces a workflow trace, and verify the expected trace appears after following the documented setup.