I am collecting data using Google's Measurement Protocol, and sending the uid parameter. This works fine. But I would like to be able to fetch the uid back from Google. I can fetch the value of a custom dimension, but I would prefer not to set cd1 = uid for every request if possible.
I notice in this question that there is a comment by @DaImTo saying that it is not possible... and I suspect he's right, but I'd like to hear from someone who knows for sure.
I don't believe it is possible to get the uid without setting it through a custom dimension.