Thanks for your answer Kevin. I actually drew the same conclusion reading some more documentation as you wrote:

Anything contained in a scoped class loader will not be visible outside of the scope

and therefore went ahead to change the architecture of my applications.

I was trying to achieve the following - having one of the scope-deployed ESB applications use a custom library for object conversion. The converter code is in a separately deployed JAR archive and was unable to convert one object to another, because it had no access to the classes from the ESB. I solved the issue by passing a ClassLoader instance from the calling code inside the ESB application to the converter object and using it there in Class.forName().

I was wondering however what are the possible ways to read a file (let's say a Java properties file) packaged inside an ESB archive. To reach it using standard "new File()" I would have to know the exact location of uncompressed .esb contents in application server's "deploy" folder. And to reach it using Class.getResource() I would have to use scope deployment (which may be undesirable) or otherwise I will get the same file for different ESB applications.