How prevalent is SSL inspection by way of certificate replacement on proxy's?

Folks:

I'm trying to get some information to see if I need to make a code change ... it relates to SSL certificate replacement on a proxy server.

I have a thick client application that runs on customers desktops ... it communicates both to the i, using JT400, and the web (using the apache httpclient library) with SSL.

We released the software a short time ago and already have a customer that encountered a problem with the SSL connection. Turns out their proxy (bluecoat) was replacing the SSL certificate that our web site presented with their own, self signed, certificate.

For the web browser that's not a problem ... the company established a policy that said the self signed certificate was trusted, so the chain was valid.

For our application, however, the self signed certificate wasn't trusted and it generated an error.

So my question is this: How prevalent is the SSL certificate replacement by proxys? Is this something we're going to encounter a lot ... or is this a fringe case?

Thanks!

david