How to properly import jar file for standalone application

I am using a websocket library containing .m files that reference a .jar package. The application will be deployed with the Application compiler, but i have a very hard time figuring it out, despite looking into all functions related to modifying the classpath. (i am about to loose it)

The project structure in folder 'main' is simple

./main.m
./HandleServer.m
./3party/Server.m (abstract handle class)
./3party/ws.jar

The code in main instantiates the HandleServer < Server, but first problem (nothing to do with jar):

The specified superclass
'Server' contains a parse
error, cannot be found on MATLAB's
search path, or is shadowed by
another file with the same name.

and but it is on the dynamic classpath in main.m:

javaclasspath('./3party')
server = HandleServer(50011, 'foo');

Because standalone, >>edit(fullfile(prefdir,'javaclasspath.txt')) I would like to circumvent (it errors too), if i right click and add folder via context menu in file explorer it works. What am I doing wrong here, the 3party folder is on the dynamic class path and not shadowed, please help?

Second question is (if i use the context menu to add Server.m to fix above), inside Server.m it references Java class inside .jar file, which is not found although i add the jar in the app compiler wizard "files required to run..".

The import command looks like:

   import io.github.jebej.matlabwebsocket.MatlabWebSocketSSLServer;

and the jar file contains a top folder 'io' and nested until the actual class 'MatlabWebSocketSSLServer.java', so the file exists inside the jar, what is wrong? The error is:

mcc -o test -W main:test -T link:exe -d /..foo../main/standalone/test/for_testing -v /..foo../main/main.m -a /..foo../main/3party -a /..foo../main/HandleServer.m
Compiler version: 6.4 (R2017a)

Dependency analysis by REQUIREMENTS.

Unexpected error while determining required deployable files. Compilation terminated. Details:
Error using getSymbolNames
Import argument "io.github.jebej.matlabwebsocket.MatlabWebSocketSSLServer" in MATLAB code '/..foo../main/3party/Server.m' cannot be found or cannot be imported.

This answer says it mcc -a should take care of it all, no need for addclasspath but not working:

https://de.mathworks.com/matlabcentral/answers/97072-how-should-i-include-a-jar-file-in-my-compiled-application-with-matlab-compiler-4-1-r14sp1