how to get Traceparent/currentTraceparent in rum agent

[Manjukb]

our app uses socket.io and elastic apm wont track socket transactions automatically
so trying to instrument code to send trace data
how to get traceparent value when i start a new transactions when i do transaction.traceparent i get null but same works in nodejs agent

		`const transaction = apm.startTransaction('message', 'socket', { managed: true })
        console.log(transaction.traceparent );`

[kirbysayshi]

I was recently wondering this too. A use case is passing a traceparent header manually to the server in the case of an unsupported technology like WebSockets.

[vigneshshanmugam]

This is a duplicate issue - #468, We will soon expose a way to set the trace propagation through the agent API.