Language identification

[dotchetter]

Hi, I'm trying to activate language identification in streaming transcriptions according to this guide:
https://docs.aws.amazon.com/transcribe/latest/dg/lang-id-stream.html

Can't see an argument for this in the CTOR. Reading this source, the header x-amzn-transcribe-identify-language is clearly not an optional from the request_shape variable of StartStreamTranscriptionRequest type.

Is there a reason for why this was omitted?