Web application hosted in OpenLiberty cannot find classes through system class loader - open-liberty

Question

I have hosted a web application in open liberty and I am trying to class load some third party java classes which are in a jar. I added the folder as a library which contain the jar file and added that library as a class loader. but i am getting a class not found exception when i try to load it.
Also when I use URLClassLoader it works perfectly fine. But i want to change the URLClassLoader to System ClassLoader
My server.xml contains below lines.
<application location="${application.name}"
type="war"
id="${application.name}"
name="${application.name}" context-root="<URL>">
<classloader apiTypeVisibility="spec, ibm-api, api, stable, third-party" commonLibraryRef="Lib"/>
</application>
<library id="Lib" apiTypeVisibility="spec, ibm-api, api, stable, third-party">
<folder dir="${wlp.install.dir}/../custom-java/" />
</library>
Any help regarding this highly appreciated.

Answer 1

If you have a jar file, you need to use <file> or <fileset> instead of <folder>.
For a single jar:
<library id="Lib" apiTypeVisibility="spec, ibm-api, api, stable, third-party">
<file name="${wlp.install.dir}/../custom-java/myjar.jar" />
</library>
For a directory with multiple jars:
<library id="Lib" apiTypeVisibility="spec, ibm-api, api, stable, third-party">
<fileset dir="${wlp.install.dir}/../custom-java/" includes="*.jar" scanInterval="5s" />
</library>
I believe <folder> is only used when you have a folder of files you want to load with Class.getResource(), or if you have a directory structure of .class files which aren't in a jar.
For more details, see the Knowledge Center
Update: When you've added a library to your application like this, you should be able to access the classes in the library just like you access classes in your application.
For example, these should work:
new MyLibraryObject()
Class.forName("com.example.MyLibraryObject")
Thread.currentThread().getContextClassLoader().loadClass("com.example.MyLibraryObject")
However, using the system classloader specifically still won't work.
In OpenLiberty, the system classloader loads a minimal set of classes. Liberty internals are loaded using OSGi which has its own set of classloaders and application classes are loaded by a special application classloader which can load the application classes, API classes and shared libraries, but doesn't have access to load any liberty internal classes.

Answer 2

After lot of fiddling around came up with the answer.
The problem was how I defined the class loader. I changed my class loader to use the Application class loader (this is what mentioned in the Azquelt reply) instead of the the system class loader.
also just adding a library path was enough. no need to specify in the class loader in the server.xml
thank you for your input #Azquelt