getRequestBodyBytesSent
Get the number of bytes sent to the network for the request body.
This is the size of the body sent, after encodings are applied, so it might be greater than the value returned by method@MessageMetrics.get_request_body_size. This value is available right before signal@Message::wrote-body signal is emitted, but you might get an intermediate value if called before.
Return
the request body bytes sent