Tim Holloway wrote:What is "minification"?
Do you mean data compression?
If so, it is hardly unexpected to see this problem. When Tomcat is in charge of transport, Tomcat can choose to compress data, based on configuration information and stated MIME types. But if Tomcat is being proxied by IIS, then it's the job of IIS to determine the compression (and encryption) of the data streams. The Tomcat-to-IIS data tunnel is not an open HTTP link and it isn't likely to be using the same protocols, but rather protocols more suitable for proxy transfers.