Builded .jar cannot find org/java_websocket/server/WebSocketServer class

Question

Any one know why i keep getting this error when running a jar? java.lang.NoClassDefFoundError: org/java_websocket/server/WebSocketServer

I added dependency and shaded the external library into .jar My dependency in pom.xml:

<dependency>
    <groupId>org.java-websocket</groupId>
    <artifactId>Java-WebSocket</artifactId>
    <version>1.5.4</version>
</dependency>