Which classpath will be searched when?

Imagine if you will:

java -cp FubarCmdLine.jar -jar Fubar.jar

Inside Fubar.jar I have a manifest

...
Class-Path:   FubarProxy.jar file:/C:/Fubar/FubarLibrary.jar

Inside FubarProxy.jar I have a manifest

...
Class-Path:  file:/C:/CustomerFubar/FubarExtension.jar

My question is, what order will the classpaths be searched? Or, more simply, what order will FubarCmdLine.jar, FubarLibrary.jar and FubarExtension.jar be searched and can I rely on that order in the future?

A little background ...

We deploy tools to customer site just by copying the jar to their server. From there it is invoked through a scheduler. The tools need to make use of classes already present on the system. These classes are usually in D:\Fubar\ but sometimes in C:\Fubar\ and, more rarely, somewhere customer specific.

We currently use a manifest classpath in the shipped jar to look in D:\Fubar then C:\Fubar but this doesn't handle the customer specific situation. Adding a -cp parameter to the launch seems to work but ALL launch scripts must be changed in this way, and if you miss one you're stuffed.

Some experimentation showed that using a special jar, a kind of classpath proxy, containing its own customer-specific manifest works well. Just add it to the tool manifest and, if it is present it will be used. My concern is that I don't actually know which is scanned first, the command-line cp, the cp in the proxy jar or the cp in the original jar.

Thanks all for your time.

Paul